From @ava@piefed.blahaj.zone source, the 10%/90% ratio went from 2.16 in 1989 to 2.14 in 2025.

Consistent with their criticism of choosing the top 10% vs the top 1-or-fewer %, the 1%/99% ratio went from 40% to 46%. The 1%/90% ratio went from 90% to 99, and the (10-1)%/90% from 127% to 114%.

That data only goes back to 1989, which is kind of late. My impression is that most of the dysfunctional growth of wealth and income inequality started late 70s/early 80s - a lot of people like to blame it on Reagan; other like to blame the gold standard - and these percentages change pretty slowly on population scale.