From the Tax Policy Center:
Myth: Americans are overtaxed.
In 2007, federal, state and local taxes claimed about $3.8 trillion, or 27 percent of U.S. gross domestic product. That's nearly $13,000 for every American. Two-thirds of tax revenues went to the federal government.
It may sound like a lot, but other developed countries collect even more. In 2006, taxes in 30 of the world's richest countries averaged 36 percent of GDP; only Mexico, Turkey, South Korea and Japan had tax rates lower than ours. And taxes in many European countries exceeded 40 percent of GDP because these nations offer more extensive government services than the United States does.
Americans do pay far more in individual income taxes than residents of other wealthy nations. Nearly 37 percent of U.S. tax revenue came from personal income taxes in 2006, about 10 percentage points more, on average, than in other industrialized countries. But we pay much less in sales taxes; 17 percent of 2006 U.S. tax receipts were from taxes on goods and services, or about half the 32 percent average for rich countries.
Bottom line: We may hate our taxes, but we pay far less than people in other wealthy countries.