The [IRS] reports that the nation's 400 highest-earning households reported an average income of $345 million in 2007 - up 31% from 2006 - and that their average tax bill fell to a 15-year low. Bloomberg writes that the elite 400's average income more than doubled that year from $131.1 million in 2001, the year Congress adopted tax cuts urged by then-President George W. Bush. Each household in the top 400 of earners paid an average tax rate of 16.6 percent, the lowest since the agency began tracking the data in 1992. Their average effective tax rate was about half the 29.4 percent in 1993, the first year of President Bill Clinton's administration. The top 400 earners received a total $138 billion in 2007, up from $105.3 billion a year earlier. On an inflation-adjusted basis, their average income grew almost fivefold since 1992. Almost three-quarters of the highest earners' income was in capital gains and dividends taxed at a 15 percent rate set as part of Bush-backed tax cuts in 2003.