If you look into the demographics here, there are some interesting stats.
People of Japanese and Chinese ancestry in America do better than those in the home country.
People of Swedish and German ancestry in America do better than those in the home country.
People of Mexican and African ancestry in America do better than those in the home country.
See a trend? Our low averages are more a result of our demography than of our failure to educate.
This was seen recently in an argument between Texans and Wisconsinites (?).
The WI folks were dissing TX for their low test scores, till somebody pointed out that blacks in TX did better than blacks in WI, hispanics in TX did better than hispanics in WI, whites in TX did better than whites in WI, etc.
But the much larger number of minorities in TX skews the results.
http://educationnext.org/are-wisconsin-schools-better-than-those-in-texas/
We no longer have an Education System we swapped it for Government Controlled "Indoctrination Centers".