An American in the top 1 percent of earners had an average income of $1.3 million in 2012, the most recent year for which data are available. Average income jumps to $30.8 million for the top 0.01 percent.
Adjusted for inflation, the top 0.01 percent's average earnings have jumped by a factor of seven since 1913. For the bottom 90 percent of Americans, average incomes after inflation have grown by a factor of just three since 1917 and have declined for the past 13 years.
Economists have long argued that a rising wealth gap has complicated the U.S. rebound from the Great Recession.
Now, an analysis by the rating agency Standard & Poor's lends its weight to the argument: The widening gap between the wealthiest Americans and everyone else has made the economy more prone to boom-bust cycles and slowed the 5-year-old recovery from the recession.