By David Cay Johnston
The author is a Reuters columnist. The opinions expressed are his own.

The U.S. tax debate tends to focus on the top 1 percent — their share of income taxes and their tax rates. Anti-tax groups encourage this focus, now embraced by the Occupy demonstrators on Wall Street and across America.

Problem is, the top 1 percent is a very misleading measure of who pays federal income taxes. It mixes doctors and billionaires, masking the taxes paid by the middle class and the affluent.

Everyone seems to know that about half of Americans paid no income taxes in 2009 and that the top 1 percent paid about 37 percent of the income taxes.

But how many people know that households making less than $75,000 collectively paid more federal income tax than those making $1 million or more?