These are household income quantiles, not personal income quantiles. It's not stated on the chart, but that lines up better with: http://en.wikipedia.org/wiki/Household_income_in_the_United_...
$1 trillion / 153 million workforce = ~$6500 / worker = $13,000 per household
It's not too hard to imagine that somehow this money tends to flow moreso towards people in the upper quintile (straight wage-earners would miss out, whereas the investing class has many avenues to receive it), so it wouldn't surprise me at all that 1 household could end up with their "share" plus that of 2 others, so: $13,000 * 3 = $39,000 household income based on govt deficit spending $112,541 - $39,000 = $73,500 household, /2 = 36,500 per person in "real", non-deficit enhanced earnings required to make the top quintile.
Made up entirely, but I don't think it is an unrealistic scenario at all. The enormous deficits we are now running can go a long way in hiding the truth for a very long time. Meanwhile, the debt grows and grows, and the interest on that debt gets larger every year. I just don't see how debt is inconsequential, but the vast majority of people seem to act as if it is (at least those who are even aware of it).
Individual wages have risen steadily since 1910, with no gaps. The household income chart is a misleading chart.
Incredibly stable since 1960.
This is a log-scale graph, which is what you want in order to compare rates of increase. You can see sort of an inflection point around the early 80s, but I'm not sure if it's significant.
This is a sum of all incomes from all possible sources devided by population.
And per capita is a simple average, while looking at medians or quintiles gives you a clearer picture. Per capita, a roomful of middle class workers all become billionaires if Bill Gates walks in.