Michael Clemens directs our attention to a February 2013 paper by Chang-Tai Hsieh, Erik Hurst, Charles I. Jones, and Peter J. Klenow, here is the abstract:
In 1960, 94 percent of doctors and lawyers were white men. By 2008, the fraction was just 62 percent. Similar changes in other highly-skilled occupations have occurred throughout the U.S. economy during the last fifty years. Given that innate talent for these professions is unlikely to differ across groups, the occupational distribution in 1960 suggests that a substantial pool of innately talented black men, black women, and white women were not pursuing their comparative advantage. This paper measures the macroeconomic consequences of the remarkable convergence in the occupational distribution between 1960 and 2008 through the prism of a Roy model. We find that 15 to 20 percent of growth in aggregate output per worker over this period may be explained by the improved allocation of talent.