from politifact.com

the United States is on the low end in terms of the overall tax burden -- 28 percent of gross domestic product in 2007, according to the Organization for Economic Cooperation and Development, compared with an average of 36 percent in the 30 OECD countries. Only South Korea, Mexico and Turkey were lower."

The income tax generates 45 percent of federal tax revenue, followed by 36 percent for payroll taxes, 12 percent for corporate income taxes, 3 percent for excise taxes and 4 percent for other taxes.

Tax revenues aren't the only form of revenues that fund the government. As we reported in an earlier item, the federal government also collects fees paid to various agencies.

In 2009, for example, the government took in the following: the U.S. Postal Service ($69 billion), Medicare premiums ($57 billion), deposits with the Federal Reserve Board ($34.3 billion), customs duties ($21.3 billion), Federal Deposit Insurance Corp. premiums and recoveries ($20.5 billion), auction proceeds from electromagnetic spectrum rights ($16.7 billion), energy sales by the Tennessee Valley Authority ($11.1 billion), natural resources royalties and revenues ($9.9 billion).

Together, these non-tax collections totaled $240 billion, an amount roughly equal to 10 percent of what taxes bring in -- which is more than pocket change.