The proportion of children born on the bottom rung of the ladder who rise to the top as adults in the U.S. is 7.5 percent—lower than in the U.K. (9 percent), Denmark (11.7), and Canada (13.5). Horatio Alger has a funny Canadian accent now. - http://www.brookings.edu/research/opinions/2016/05/17-in-defense-of-immigrants-reeves