<< the probability for children to attain a higher income than their parents has dropped dramatically -- from more than 90 percent for children born in 1940 to 50 percent for children born in the 1980s >>
Upward mobility has fallen sharply in US: study. Apr. 24, 2017
https://m.phys.org/news/2017-04-upward-mobility-fallen-sharply.html
Raj Chetty, David Grusky, et al. The fading American dream: Trends in absolute income mobility since 1940. Science 28 Apr. 2017:
Vol. 356, Issue 6336, pp. 398-406
DOI: 10.1126/science.aal4617.