The data comes from the Congressional Budget Office. The numbers show after-tax income for quintiles of the population. The numbers are expressed in 2006 dollars to factor out inflation.
I'll defer any commentary because it's a "res ipse loquitur" table. Whether you think the income disparity in this country is good or bad, justified or not, is not the point here. The point of this table is that that disparity has been increasing.
Via Swimming Freestyle.