Mark Thoma is wishing he had already found time to read Piketty and Saez (2006), "The Evolution of Top Incomes: A Historical and International Perspective" (Cambridge: NBER WP 11955:
Abstract: This paper summarizes the main findings of the recent studies that have constructed top income and wealth shares series over the century for a number of countries using tax statistics. Most countries experience a dramatic drop in top income shares in the first part of the century due to a precipitous drop in large wealth holdings during the wars and depression shocks. Top income shares do not recover in the immediate post war decades. However, over the last 30 years, top income shares have increased substantially in English speaking countries but not at all in continental Europe countries or Japan. This increase is due to an unprecedented surge in top wage incomes starting in the 1970s and accelerating in the 1990s. As a result, top wage earners have replaced capital income earners at the top of the income distribution in English speaking countries. We discuss the proposed explanations and the main questions that remain open.
Thoma reproduces what are by far the most interesting figures in Piketty and Saez, which show that the pretax income share of the top 1% of the American income distribution jumped from 8% in 1980 to 9% in 1985 to 13% in 1990 to 17% in 2000 to 14% today. Over the same period the income share of the next 4% has risen from 13% to 15%, and the income share of the still next 5% has stayed at 12%. The top tenth of the American income distribution increased its share from 33% in 1980 to 41% today--with three-quarters of that increase going to the top 1% and fully one-quarter of that increase going to the top 0.01%.
What skills and assets do the top 1% of America's pretax income distribution have today that lead the market to grant them 14% of total income, when their counterparts back in 1980 were granted only 8% of total income? What skills and assets do the top 0.01% of the American pretax income distribution--that's 12,000 tax units--that led the market to grant them 100 times average income in 1980, and 300 times average income today?