The Shrinking Middle Class: By the Numbers

The American middle-class ideal was forged in the decades after World War II, when economic growth and wage increases climbed in lockstep for nearly 30 years. That pairing dissolved abruptly in the 1970s. Between 1973 and 2017, according to the Economic Policy Institute, the productivity of the economy grew 77%—but average compensation rose only 12.4%, adjusted for inflation.
Read more: http://fortune.com/longform/shrinking-middle-class-math?source=Snapzu