Tyler Cowen has an excellent article posted about African immigration. I have not done the research to confirm this is true or not but my personnel experiences would suggest he is correct. In college and in my master program, African immigrants were always the top performers. Cowen writes:
One of the most striking facts about immigration to the U.S., unbeknownst even to many immigration advocates, is the superior education of Africans coming to this country. If we consider adults age 25 or older, born in Africa and living in the U.S., 41.7 of them have a bachelor’s degree or more, according to 2009 data. For contrast, the native-born population has a bachelor’s degree or more at the much lower rate of only 28.1 percent in these estimates, and foreign-born adults as a whole have a college degree at the rate of 26.8 percent, both well below the African rate.
How about high school degrees? About one-third of immigrants overall lack this credential, but only 11.7 percent of African-born migrants don’t have a high school degree. That’s remarkably close to the rate for native-born Americans, estimated at 11.4 percent.