The adjusted gross income of the country's top 400 taxpayers totaled almost $70 billion in 2000, according to the IRS, for an average of $173.9 million. The richest 400 in 1992 accumulated just under $19 billion, for an average of only $46.8 million.
Over the nine-year period, the minimum adjusted gross income to get on the top 400 list more than tripled, from $24.4 million to $86.8 million.
In 2000, the 400 paid 22.3 percent of their income to federal income tax coffers, down from 26.4 percent in 1992.
The richest 400 made 1.09 percent of U.S. income in 2000, more than double the percentage in 1992, when they accounted for just 0.52 percent, the IRS said.