From 1950 to 1980, the top 1 percent represented about 10 percent of Americans’ income; by 2000, this had increased to about 20 percent, where it’s remained, estimate economists Emmanuel Saez and Thomas Piketty.


http://www.washingtonpost.com/opinions/buffett-tax-and-truth-in-numbers/2012/01/29/gIQAikL5aQ_story.html?hpid=z2