nih.gov: History & Trends
How this site has changed over time. The weekly overview answers "what should I fix now?"; this page answers "how are we trending?"
Tracking since 2026-W25 — 16 weeks recorded. Accessibility score is worsening (-4 pts since 2026-W36). Download the full trend series: CSV · JSON.
How the latest week compares
Latest week (2026-W40) vs. earlier look-back windows. positive/negative is relative to each measure — coloured by better or worse
| Measure | Now | vs 4 wk ago | vs 13 wk ago |
|---|
| Accessibility score | 59 | -4 worse | -26 worse |
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| Median axe violations / page | 9 | +1 worse | +6 worse |
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| Median page weight (KB) | 62 KB | +2 KB worse | -3 KB better |
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| Reading ease (Flesch) | 47.5 | +4.5 better | n/a |
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| Standards checks passing (%) | 71% | -2% worse | n/a |
|---|
Accessible? — severity over time
Pages affected by axe severity over 16 weeks (lower is better)
Pages affected by axe severity, by week
| Week | Critical | Serious | Moderate | Minor |
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| 2026-W25 | 0 | 6 | 10 | 1 |
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| 2026-W26 | 0 | 1 | 1 | 0 |
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| 2026-W27 | 0 | 1 | 2 | 0 |
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| 2026-W28 | 0 | 1 | 1 | 0 |
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| 2026-W29 | 102 | 3296 | 6930 | 276 |
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| 2026-W30 | 128 | 3359 | 6850 | 351 |
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| 2026-W31 | 120 | 3360 | 6899 | 351 |
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| 2026-W32 | 118 | 3352 | 6923 | 349 |
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| 2026-W33 | 0 | 24 | 55 | 1 |
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| 2026-W34 | 1 | 22 | 48 | 4 |
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| 2026-W35 | 1 | 21 | 45 | 1 |
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| 2026-W36 | 2 | 22 | 50 | 4 |
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| 2026-W37 | 2 | 23 | 57 | 0 |
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| 2026-W38 | 1 | 24 | 50 | 3 |
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| 2026-W39 | 0 | 24 | 53 | 6 |
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| 2026-W40 | 0 | 17 | 28 | 2 |
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Fast? — Lighthouse over time
Lighthouse category scores over 16 weeks
Lighthouse category scores by week
| Week | Performance | Accessibility | Best practices | SEO |
|---|
| 2026-W25 | n/a | n/a | n/a | n/a |
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| 2026-W26 | n/a | n/a | n/a | n/a |
|---|
| 2026-W27 | n/a | n/a | n/a | n/a |
|---|
| 2026-W28 | n/a | n/a | n/a | n/a |
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| 2026-W29 | 61 | 95 | 96 | 100 |
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| 2026-W30 | 44 | 95 | 96 | 100 |
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| 2026-W31 | 43 | 95 | 96 | 100 |
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| 2026-W32 | 46 | 95 | 96 | 100 |
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| 2026-W33 | 37 | 95 | 77 | 100 |
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| 2026-W34 | 34 | 93 | 77 | 96 |
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| 2026-W35 | 39 | 95 | 77 | 100 |
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| 2026-W36 | 30 | 96 | 77 | 100 |
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| 2026-W37 | n/a | n/a | n/a | n/a |
|---|
| 2026-W38 | 35 | 95 | 77 | 100 |
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| 2026-W39 | 30 | 95 | 77 | 100 |
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| 2026-W40 | 35 | 96 | 77 | 96 |
|---|
Lighthouse trend points are based on sampled pages and can vary week-to-week depending on which pages were sampled.
Sustainable? — page weight, requests & carbon over time
Median page weight (KB) over 16 weeks — better (65 KB → 62 KB)
Median page weight (KB) by week
| Week | Median page weight (KB) |
|---|
| 2026-W25 | 65 KB |
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| 2026-W26 | 65 KB |
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| 2026-W27 | 65 KB |
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| 2026-W28 | 63 KB |
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| 2026-W29 | 2040 KB |
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| 2026-W30 | 2052 KB |
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| 2026-W31 | 1397 KB |
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| 2026-W32 | 2076 KB |
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| 2026-W33 | 63 KB |
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| 2026-W34 | 63 KB |
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| 2026-W35 | 63 KB |
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| 2026-W36 | 60 KB |
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| 2026-W37 | 62 KB |
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| 2026-W38 | 62 KB |
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| 2026-W39 | 62 KB |
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| 2026-W40 | 62 KB |
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Median requests per page over 16 weeks — unchanged
Median requests per page by week
| Week | Median requests per page |
|---|
| 2026-W25 | 7 |
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| 2026-W26 | 7 |
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| 2026-W27 | 7 |
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| 2026-W28 | 7 |
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| 2026-W29 | 98 |
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| 2026-W30 | 98 |
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| 2026-W31 | 99 |
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| 2026-W32 | 98 |
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| 2026-W33 | 6 |
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| 2026-W34 | 7 |
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| 2026-W35 | 6 |
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| 2026-W36 | 6 |
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| 2026-W37 | 6 |
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| 2026-W38 | 6 |
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| 2026-W39 | 6 |
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| 2026-W40 | 7 |
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Mean CO₂ per page (g) over 16 weeks — better (0.0282 g → 0.0239 g)
Mean CO₂ per page (g) by week
| Week | Mean CO₂ per page (g) |
|---|
| 2026-W25 | 0.0282 g |
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| 2026-W26 | 0.0098 g |
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| 2026-W27 | 0.0098 g |
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| 2026-W28 | 0.0096 g |
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| 2026-W29 | 0.2785 g |
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| 2026-W30 | 0.2821 g |
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| 2026-W31 | 0.2597 g |
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| 2026-W32 | 0.2929 g |
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| 2026-W33 | 0.0125 g |
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| 2026-W34 | 0.0126 g |
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| 2026-W35 | 0.0106 g |
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| 2026-W36 | 0.0096 g |
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| 2026-W37 | 0.0102 g |
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| 2026-W38 | 0.0114 g |
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| 2026-W39 | 0.0208 g |
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| 2026-W40 | 0.0239 g |
|---|
Findable? — readability over time
Reading ease (Flesch) over 14 weeks — better (43 → 47.5)
Reading ease (Flesch) by week
| Week | Reading ease (Flesch) |
|---|
| 2026-W25 | 43 |
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| 2026-W28 | 49.5 |
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| 2026-W29 | 45 |
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| 2026-W30 | 44 |
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| 2026-W31 | 44 |
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| 2026-W32 | 43.9 |
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| 2026-W33 | 47 |
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| 2026-W34 | 39.2 |
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| 2026-W35 | 41 |
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| 2026-W36 | 43 |
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| 2026-W37 | 43.3 |
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| 2026-W38 | 42.6 |
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| 2026-W39 | 43.6 |
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| 2026-W40 | 47.5 |
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Reading grade (Flesch-Kincaid) over 14 weeks — worse (12 → 12.3)
Reading grade (Flesch-Kincaid) by week
| Week | Reading grade (Flesch-Kincaid) |
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| 2026-W25 | 12 |
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| 2026-W28 | 10.5 |
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| 2026-W29 | 12 |
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| 2026-W30 | 12.5 |
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| 2026-W31 | 12.4 |
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| 2026-W32 | 12.5 |
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| 2026-W33 | 12 |
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| 2026-W34 | 14.5 |
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| 2026-W35 | 14 |
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| 2026-W36 | 13 |
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| 2026-W37 | 12.2 |
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| 2026-W38 | 12.5 |
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| 2026-W39 | 12.6 |
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| 2026-W40 | 12.3 |
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Words per page (median) over 15 weeks — 275 → 729
Words per page (median) by week
| Week | Words per page (median) |
|---|
| 2026-W25 | 275 |
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| 2026-W26 | 23 |
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| 2026-W28 | 417 |
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| 2026-W29 | 731 |
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| 2026-W30 | 744 |
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| 2026-W31 | 732 |
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| 2026-W32 | 734 |
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| 2026-W33 | 712 |
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| 2026-W34 | 649 |
|---|
| 2026-W35 | 600 |
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| 2026-W36 | 751 |
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| 2026-W37 | 777 |
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| 2026-W38 | 777 |
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| 2026-W39 | 717 |
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| 2026-W40 | 729 |
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Trustworthy? — technology & standards over time
Technologies detected over 12 weeks — unchanged
Technologies detected by week
| Week | Technologies detected |
|---|
| 2026-W28 | 14 |
|---|
| 2026-W29 | 14 |
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| 2026-W30 | 14 |
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| 2026-W31 | 14 |
|---|
| 2026-W32 | 14 |
|---|
| 2026-W33 | 14 |
|---|
| 2026-W34 | 14 |
|---|
| 2026-W35 | 14 |
|---|
| 2026-W36 | 14 |
|---|
| 2026-W37 | 14 |
|---|
| 2026-W39 | 14 |
|---|
| 2026-W40 | 14 |
|---|
Standards checks passing (%) over 14 weeks — worse (73% → 71%)
Standards checks passing (%) by week
| Week | Standards checks passing (%) |
|---|
| 2026-W25 | 73% |
|---|
| 2026-W26 | 56% |
|---|
| 2026-W29 | 56% |
|---|
| 2026-W30 | 72% |
|---|
| 2026-W31 | 72% |
|---|
| 2026-W32 | 72% |
|---|
| 2026-W33 | 73% |
|---|
| 2026-W34 | 73% |
|---|
| 2026-W35 | 72% |
|---|
| 2026-W36 | 73% |
|---|
| 2026-W37 | 73% |
|---|
| 2026-W38 | 72% |
|---|
| 2026-W39 | 73% |
|---|
| 2026-W40 | 71% |
|---|
Security checks passing (%) over 12 weeks — worse (75% → 63%)
Security checks passing (%) by week
| Week | Security checks passing (%) |
|---|
| 2026-W25 | 75% |
|---|
| 2026-W29 | 88% |
|---|
| 2026-W30 | 88% |
|---|
| 2026-W31 | 88% |
|---|
| 2026-W32 | 88% |
|---|
| 2026-W33 | 63% |
|---|
| 2026-W34 | 63% |
|---|
| 2026-W36 | 63% |
|---|
| 2026-W37 | 63% |
|---|
| 2026-W38 | 63% |
|---|
| 2026-W39 | 63% |
|---|
| 2026-W40 | 63% |
|---|