In 2001, the top quintile (20%) averaged $133,700 in personal income after taxes. This group's share of the total income tax liability was 65.3%. The fourth quintile made ~$61,000 after taxes, and shouldered 18.5% of the income tax burden. The middle class made ~$43,700 and accounted for (drumroll...) 10% of the total burden. Second quintile paid for 5%, lowest quintile, 1%.
The top 1% of wage earners paid 22.7% of the total income tax liability. The top 10% paid for 50% of the total.
For personal income taxes only:
Top quintile ($133,700): 82.5%
Fourth quintile: 14.3%
Third quintile (blue collar working stiffs): 5.2%
Second quintile: .3%
First quintile: (-)2.3%
Share of [evil]corporate[/evil] income tax:
Fifth quintile: 82.6% (with 51.8% coming from the top 1%)
Fourth: 7.7%
and downward.
Congressional Budget Office docs