Quantifying rate of language change in Rust! https://words.steveklabnik.com/how-often-does-rust-change
Putting numbers on this is hard, but produces some interesting methodologies.
miniblog.
Related Posts
https://blog.phronemophobic.com/dewey-analysis.html is an absolutely delightful post quantifying Clojure usage.
Functions outnumber macros 20:1, the most popular single letter variable is x, and 63% of projects have zero mutable references!
https://www.modulecounts.com/ look at the number of packages released per programming language. It's a great way of quantifying language sizes.
The PHP ecosystem is way bigger than e.g. Ruby, but I hear about it much less often.
Quantifying Gnome contributions by frequency, tenure, and affiliated companies:
https://hpjansson.org/blag/2020/12/16/on-the-graying-of-gnome/
Whilst the methodology can't be perfect, it's a nice way of measuring contribution trends.