皮尤研究：House gets younger, Senate gets older:

House gets younger, Senate gets older: A look at the age and generation of lawmakers in the 118th Congress

https://www.pewresearch.org/short-reads/2023/01/30/house-gets-younger-senate-gets-older-a-look-at-the-age-and-generation-of-lawmakers-in-the-118th-congress/