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

https://eduardosnicechat.publishlane.com/posts/why-isn-t-baidu-in-the-ledger-even-though-it-hit-9-on-lmarena

The AI Models Index tracks premium model releases from 15 labs since 2023, verifying launch dates and using blind votes to ensure accuracy. Updated every two weeks, it shows a steady pace—like the 4.5 days between GPT-5.1 and GPT-5