Have a gander at this link. Apparently, “people of color” is a 100% American euphemism, as “coloreds” is a 100% American slur. “Negroes”, however, is a somewhat more international slur, being searched most often in Canada, but being found in the U.S., Brazil, India, Australia, and the U.K. as well. “Blacks” is a rather international racial description, being searched most often in Rhodesia, New Zealand, Gabon&Cameroon, Kenya, and Paupa New Guinea.
As “people of color” is a 100% American euphemism, judging from this link, it seems that it is searched more often than “african-americans” (with dash), and that both terms are searched far less often than “african americans” (without dash). The term “african americans” (without dash) is always searched in a yearly cycle, with February (Black History Month) being the peak of the cycle and August being the trough.
I (a white male residing in the U.S.) prefer the term “blacks” for members of the race. Not all Africans are Sub-Saharan (or black), the terms “coloreds” and “negroes” are generally looked down upon as relics of an earlier time, and the term “people of color” is ridiculously long, might include Indian Indians, and is an exclusively American euphemism. Though “blacks” is hardly a technically correct description for members of the black race in the U.S. (most U.S. blacks are brown-skinned), it seems that this is the term most often used to describe blacks in majority-black countries.