What percentage of people were actually paying 90% in the 50s? Back then it was a lot easier to hide income.
"Hauser's law is the proposition that, in the United States, federal tax revenues since World War II have always been approximately equal to 19.5% of GDP, regardless of wide fluctuations in the marginal tax rate.[1] Historically, since the end of World War II, federal tax receipts as a percentage of gross domestic product averaged 17.9%, with a range from 14.4% to 20.9% between 1946 - 2007.[2]"
https://en.wikipedia.org/wiki/Hauser's_law
