This is my own chart—showing the dramatic changes in the average incomes (excluding capital gains) of the top 1 percent compared to those of the bottom 90 percent, expressed as a ratio, from 1920 to 2015—from the World Wealth and Income Database.
Thus, for example, the ratio first peaked in 1928 (when, on average, top 1-percent incomes were 32.7 times those of the average of the bottom 90 percent), eventually decreased to a low in 1972 (of 10.2), then peaked once again in 2012 (with a value of 32.5). As of 2015, the ratio stood at 31.7.
Emmanuel Saez, Thomas Piketty, and the rest of the team need to be credited for making their data available. Readers should feel free to use this chart and reproduce it as they wish. . .