In 1971 a child from the poorest fifth had an 8.4% chance of making it to the top quintile. For a child born in 1986 the odds were 9%. The study confirms previous findings that America’s social mobility is low compared with many European countries. (In Denmark, a poor child has twice as much chance of making it to the top quintile as in America.) But it challenges several smaller recent studies that concluded that America had become less socially mobile.

for reference see: https://en.wikipedia.org/wiki/Larry_Ellison