New Internal Revenue Service data show that in 2005 the most affluent 1 percent of Americans earned 21.2 percent of all U.S. income, a postwar record, Reuters reported.

This marked an increase from the 19 percent reported for 2004, and indicates expanding income inequality between economic classes in the United States.

The IRS report also found a decrease in relative income for the bottom 50 percent of Americans. That group’s earnings were down to 12.8 percent of all U.S. income in 2005 from 13.4 percent in 2004. Though the IRS statistics date back only to 1986, academic research suggests that the 1920s was the last time the rich had such a high portion of America’s income.

A Wall Street Journal article quoted, President Bush as saying that the earnings disparity was due to “skills gaps” between classes. The article also said that though the IRS did not specify the cause of rising income for the wealthy, the rise in stock prices probably played a role.