Great Graphic: Early Investments in Human Capital?

This Great Graphic was posted on the Washington Post's Wonkblog by Dylan Matthews. It looks at some comparative figures for expenditures on early education. 

The results show the US has among the lowest enrollment in pre-school for 3-4-year-olds (compares to 100% in Sweden and France respectively).   

One of the reasons for the low enrollment in the US is that a relatively high percent of the costs are born privately (19%). This makes the gross disparity of income even more stark and suggests the replication of class relations begins very early.   

Overall, a relatively low share of GDP (0.4) is spent on pre-school and the teacher-child ratio is relatively high at 115. 

Early childhood education need not be understood as simply the consumption of glorified day care services, though there is that component.  It can be conceived as an early investment generating a number of positive externalities.