Gross Domestic Income, adjusted by the GDP Deflator, and divided by population to give a per capita result. Then the growth is averaged out over ten years. All figures are quarterly.
Gross Domestic Income
So what you're seeing in the graph at each point (quarters of a particular year) is how the US economy has performed over the previous ten years. The downward lines reflect the various recessions that have hit since 1962 and broadly match the NBER definitions.
What is clear from the graph above is that the years following the 2008 recession have seen a deep and long-term collapse in per capita economic growth. Moreover, what has been experienced since 2008 has been unique in that the economic trough has not recovered - the only other comparable event was the 1973 oil crisis and its aftermath, which permanently capped per capita growth to around 30%, making the 1962-1973 period a "golden age" in comparison.
(Why GDI and not GDP? See Nalewaik)