Percentage distribution of U.S. aggregate household income, by income tier, 1970-2010 (Graph)
from David Ruccio
In the below chart, the middle tier is defined as those living in households with an annual income that is 67 percent to 200 percent of the national median; the upper tier is made up of those in households above the 200 percent threshold, and the lower tier is made up of those below the 67 percent threshold.
What the Pew Research Center analysis finds is that upper-income households accounted for 46 percent of U.S. aggregate household income in 2010, compared with 29 percent in 1970. Middle-income households claimed 45 percent of aggregate income in 2010, compared with 62 percent in 1970. Lower-income households had 9 percent of aggregate income in 2010 and 10 percent in 1970.