The AI Models Index keeps track of premium releases from 15 labs since 2023,...

https://deansinspiringperspective.hexaforgey.com/posts/why-did-gemini-s-lmarena-numbers-not-match-published-snapshots

The AI Models Index keeps track of premium releases from 15 labs since 2023, verified with blind-vote checks and accurate dates. Updated every two weeks, it shows how model development speeds up—GPT-5.2 launched just 4.5 days after GPT-5