Similar to my graphs here, LK shows a break in median family income, as compared to GDP/family or, average family income. Check it out.
The vertical line on this graph indicates an inflection point of 1973. You could perhaps move it out to the next bump, if you squint, but not much further. Irrespective of that detail, what this means, simply, is that the already wealthy have captured more of the pie since the break point. Notice also that 1) the most recent decade is almost flat and 2) The Clinton years were a lot better than anything else after the break.
Of course, we knew all this, no matter how much regressives are in denial.
Update (2/2 7:30 pm) : Krugman references this same chart, but cuts across it differently. His point (emphasis added):
The rise in prices implied by real GDP numbers is measured by the GDP deflator, while the rise in incomes as calculated by the Census involves dividing by the CPI. And while those two price measures matched very well pre-1973, since then, not so much . . .
He shows it in a graph, and mentions 1973, since that is LK's chosen break point. (In both the graphs PK shows, the break is clearly much closer to 1980.) Whatever else this might mean, it illustrates yet another difference in the world before and after 1980-ish.
I've eyeballed trend lines in LK's graph breaking around 1980. Pick whichever break point you prefer. Either way the slope difference before and after is striking.