There is a huge difference between top marginal rates and actual effective tax rates. Since 1950, federal taxes have consumed 17 to 20 percent of GDP in taxes. Most economists are opposed to very high marginal tax rates though due to the inefficiencies they introduce - compensation being moved to non-salary, money wasted on CPAs, lawyers and lobbying congress for special deductions, dead weight losses for economic activity that isn't done, etc.
Currently the effective rates are fairly close to the past for high wage earners, lower for low wage earners.
>...In 1958, approximately two million filers (4.4% of all taxpayers) earned the $12,000 or more for married couples needed to face marginal rates as high as 30%. These Americans paid about 35% of all income taxes. And now? In 2010, 3.9 million taxpayers (2.75% of all taxpayers) were subjected to rates that were 33% or higher. These Americans—many of whom would hardly call themselves wealthy—reported an adjusted gross income of $209,000 or higher, and they paid 49.7% of all income taxes.
>In contrast, the share of taxes paid by the bottom two-thirds of taxpayers has fallen dramatically over the same period. In 1958, these Americans accounted for 41.3% of adjusted gross income and paid 29% of all federal taxes. By 2010, their share of adjusted gross income had fallen to 22.5%. But their share of taxes paid fell far more dramatically—to 6.7%. The 77% decline represents the single biggest difference in the way the tax burden is shared in this country since the late 1950s.
http://www.wsj.com/articles/SB100014241278873247051045781516....