http://www.irs.gov/pub/irs-soi/00in11si.xls
You will notice that the $50k to $500k income bracket account for 57.8% of all revenue before tax credits.
$50k is average Joe salary especially with two incomes, even $400k isn't far fetched so this whole.. "the wealthy needs tax cuts because they pay a proportionate number of taxes" is BS.
Want to know the income bracket with the biggest tax burden?
$100k to $200k -
The #2 tax bracket is $50k to $75k.