Two factors accounted for the changing distribution ofmarket income. One was an increase in the concentrationof each source of market income, which consists of labor income (such as cash wages and salaries and employer-paid health insurance premiums), business income, capital gains, capital income, and other income. All of those sources of market income were less evenly distributed in 2007 than they were in 1979.
The other factor leading to an increased concentration of market income was a shift in the composition of that income. Labor income has been more evenly distributed than capital and business income, and both capital income and business income have been more evenly distributed than capital gains. Between 1979 and 2007, the share of income coming from capital gains and business income increased, while the share coming from labor income and capital income decreased.
Chart showing income growth 1979 - 2007 for each quintile and the top 1% on this page. Page 'x' (as in small Roman numeral 5).
I posted the link to the actual CBO report for everyone's future reference.
Please note: Income is for the period of 1979 - 2007 - BEFORE the Big Recession, BEFORE 25 MILLION became under- or unemployed, BEFORE Wall Street and the banks let the economy tank.