Someone very clever (Mike Kimel) graphed top tax rates vs. economic growth. Someone else graphed median tax rate vs. economic growth. This median rate included all taxes, not just income. Tax rate and gdp are correllated, if you're curious, and the winning median tax rate is 25% and the best top tax rate is 65%. So. raise the rates on the wealthy and drop them on the middle class already.
Here's the fascinating work.