Krugman:

In fact, let me start this blog off with a chart that’s central to how I think about the big picture, the underlying story of what’s really going on in this country. The chart shows the share of the richest 10 percent of the American population in total income – an indicator that closely tracks many other measures of economic inequality – over the past 90 years, as estimated by the economists Thomas Piketty and Emmanuel Saez.