Not too many. Earlier generation born in 1970s, especially in the North of Vietnam, likes Modern Talking. Because at that time they started to change the foreign language in their school from Russian into English. Modern Talking is easy-listening pop music, language and pronouciation are clear, melody is easy to remember, music is pop, a kind of new trend to them. Not only Modern Talking, also Boney M, and later Micheal Learn Rock. All are the same reason.