The 21st century Gilded Age party really got going before the U.S. economy went bust.

It was a party disproportionately enjoyed by high-income Americans, the 400 wealthiest of which actually doubled their share of all U.S. income between 1996 and 2006, new statistics released by the Internal Revenue Service show.

And during the first six years of George W. Bush's presidency, the average income of those 400 people actually doubled to $263.3 million, according to the data.