The AI Models Index monitors premium model releases from 15 labs since 2023,...

https://source-wiki.win/index.php/What_Happened_to_GPT-5_vs_GPT-4.5_Lead_Over_Time%3F

The AI Models Index monitors premium model releases from 15 labs since 2023, verifying launch dates and using blind-vote checks for accuracy. Updated every two weeks, it shows a 56% improvement rate over time