It is no secret that the gap between the rich and the poor has grown, but the extent to which the richest are leaving everyone else behind is not widely known. The people at the top of America's money pyramid have so prospered in recent years that they have pulled far ahead of the rest of the population. They have even left behind people making hundreds of thousands of dollars a year. The share of the nation's income earned by those in this uppermost category has more than doubled since 1980, to 7.4 percent in 2002. The share of income earned by the rest of the top 10 percent rose far less, and the share earned by the bottom 90 percent fell. Under the Bush tax cuts, the 400 taxpayers with the highest incomes - a minimum of $87 million in 2000, the last year for which the government will release such data - now pay ... taxes amounting to virtually the same percentage of their incomes as people making $50,000 to $75,000. From 1950 to 1970 ... for every additional dollar earned by the bottom 90 percent, those in the top 0.01 percent earned an additional $162. From 1990 to 2002, for every extra dollar earned by those in the bottom 90 percent, each taxpayer at the top brought in an extra $18,000. An Internal Revenue Service study found that the only taxpayers whose share of taxes declined in 2001 and 2002 were those in the top 0.1 percent. Some of the wealthiest Americans, including Warren E. Buffett, George Soros and Ted Turner, have warned that such a concentration of wealth can turn a meritocracy into an aristocracy and ultimately stifle economic growth.