I don't have a good answer to your question here are some results from a quick google search:

https://blog.prepscholar.com/average-sat-scores-over-time

I think a sometimes-easy-to-overlook factor is that many state flagship institutions like UT-Austin have a strong bias or preference for in-state applicants. Famously, I remember being told that out-of-state applicants to my state's big, somewhat well-known, public university needed better credentials than highly selective private institutions required/recommended . . .