All of the gains in wealth accrued to the upper fifth, with 40.2 percent of the gains going to the upper 1 percent and 41.5 percent going to the next wealthiest 4 percent of households. This translated to gains of $4.5 million per household in the richest 1 percent and a gain of roughly $1.2 million per household in the next richest 4 percent of households.
In other words, the richest 5 percent of households obtained roughly 82 percent of all the nation’s gains in wealth between 1983 and 2009. The bottom 60 percent of households actually had less wealth in 2009 than in 1983, meaning they did not participate at all in the growth of wealth over this period.
To emphasize, this isn't a measure of what people had in 1983, at the start of the period the graph represents. It says, if you were in the top 5 percent in 1983, how much of the wealth that the country gained went to you? And the answer to that is almost all of it.
As we know, 2009 was an especially bad year, with median household wealth having declined from its 2005 point due to the housing collapse and other factors. But it wasn't bad enough to account for the massive growth of inequality in this graph—that has been the work of a generation and more.