I found this at the National Bureau of Economic Research. The authors of the paper Where Did the Productivity Growth Go? Inflation Dynamics and the Distribution of Income are investigating why a bigger share of econcomic growth has been captured by high income earners. From the abstract of this paper:
A basic tenet of economic science is that productivity growth is the source of growth in real income per capita. But our results raise doubts by creating a direct link between macro productivity growth and the micro evolution of the income distribution. We show that over the entire period 1966-2001, as well as over 1997-2001, only the top 10 percent of the income distribution enjoyed a growth rate of real wage and salary income equal to or above the average rate of economy-wide productivity growth . . . We distinguish two complementary explanations, the "economics of superstars," i.e., the pure rents earned by sports and entertainment stars, and the escalating compensation premia of CEOs and other top corporate officers. These sources of divergence at the top, combined with the role of deunionization, immigration, and free trade in pushing down incomes at the bottom, have led to the wide divergence between the growth rates of productivity, average compensation, and median compensation.