Mitt Romney is a rich man. But exactly how rich, when compared with the rest of us?

Had he made more than $10 million in 2009, Romney's income would have ranked in the top 0.006 percent of U.S. earnings. He made more than twice that in 2010 and 2011.

Romney's current rank is impossible to calculate, as the most recent Internal Revenue Service statistics are available only for tax years 2009 and before. The 0.006 percent figure is calculated from the number of U.S. tax filers (8,274) who made more than $10 million in 2009 out of about 140 million total tax returns filed that year. (That number is significantly lower than the total U.S. population, due in large part to joint filings.) The IRS does not break down income strata above $10 million in its yearly findings.

Romney made $21.7 million in 2010, and $20.9 million in 2011, according to 2010 returns and 2011 estimates released today by his presidential campaign, almost all of it from investments.

Given that the IRS has no statistics for tax year 2010, it's impossible to know where Romney currently ranks, and top earnings fluctuate year to year. In 2008, for instance, 13,480 people made more than $10 million, more than  5,000 more than in 2009. In 2007, 18,394 were in the $10 million club.

In 2009, the average U.S. income was $54,000 for all filers, single and joint.

Romney paid an effective tax rate of 13.9 percent in 2010, and while that figure has become the topic of much discussion during the past several weeks of the campaign, it's actually higher than the average rate paid by Americans. The average U.S. tax filer paid an 11 percent effective rate in 2009, according to a breakdown of IRS statistics by the Tax Foundation.

UPDATE : A previous version of this post misrepresented Romney's percentile by two decimal points.