Between about 1980 and 2000 the total number of foreign born persons 18 and over without a high school degree tripled in size to a peak of about 8 million. Then it declined. The number of foreign-born persons with at least a college has risen by decade at an accelerated pace.  This is in part due to the rise in higher education among countries where immigrants are increasingly coming from (Asia), plus their higher educaiton level to begin with compared to Latin America.  I call this part of the normalization of the immigrant population, to adhere closer to the socio-economic profiles of U.S. born Americans.