NEW YORK (CNN/Money) - The rich got richer in 2000, according to a study by the Internal Revenue Service released Wednesday night.

A separate IRS report released Thursday showed that in 2000 there were nearly 2.8 million "high-income" returns, those with adjusted gross income of at least $200,000. That's a 14.1 percent increase from 1999 (the total number of filed returns increased just 1.8 percent in that time).

The first study shows that in 2000 the wealthiest 400 taxpayers in the United States accumulated nearly $70 billion in adjusted gross income. That marked 1.1 percent of total AGI versus 0.5 percent in 1992.

Members of this elite group had AGI of at least $86.8 million, a big increase from $67.4 billion in 1999. The IRS did not say how much income the No. 1 filer had.

Though its share of total reported AGI more than doubled, the group's share of the total tax burden grew at a slower pace. The group's share of the tax burden grew to 1.6 percent from 1.04 percent in 1992. The average tax rate for the group, meanwhile, declined to 22.3 percent in 2000, from 26.4 percent in 1992 and a high of 29.9 percent in 1995.

Had President Bush's latest tax cuts been in effect in 2000, the amount of taxes paid by the wealthiest Americans would have dropped an additional 20 percent, according to analysis by the New York Times.

According to the IRS, here were the key sources of income for the wealthiest 400 taxpayers and how they changed as a percentage of the group's AGI.

Salaries and wages: 16.7 percent of AGI in 2000 versus 26.2 percent in 1992.

Long-term capital gains: 64 percent in 2000 versus 33 percent in 1992.

Taxable interest: 3.9 percent in 2000 versus 7.4 percent in 1992.

Dividends: 2.8 percent in 2000 versus 5.8 percent in 1992.