I seriously doubt there are many societies in which those in the bottom 20% go to the top 20%; especially when 60% of those at the bottom do not work. What is more important is that those on the bottom rose to higher quintiles. According to the Treasury Department study using IRS data:
--50% of those in the bottom quintile moved to a higher income category within 10 years
--of those in the top 1/100 of one percent only 25% remained there within 10 years
--The degree of mobility among income groups is unchanged from the prior decade (1987 through 1996).
--Median real incomes of all taxpayers increased by 24 percent after adjusting for inflation
--Median incomes of those initially in the lower income groups increased more than the median incomes of those initially in the high income groups.
https://www.treasury.gov/press-center/press-releases/Pages/hp673.aspx