Do you have a source? The data that I've seen shows that the very rich pay about the same effective rate as back in the '50s. The rates were higher in the '50s, but the exemptions were much more liberal.
http://www.facethefactsusa.org/facts/a-tax-impact-from-grand...
http://www.heritage.org/federalbudget/top10-percent-income-e...
Here's another take on U.S. taxation: https://www.americanprogress.org/issues/tax-reform/news/2011...