black man vs kaffir

black man

noun
  • Used other than figuratively or idiomatically: see black, man. 

  • A male adult member of an ethnic group having dark pigmentation of the skin, typically of sub-Saharan African descent; or the appearance thereof. 

kaffir

noun
  • A black person. 

  • South African mining shares 

  • A member of the Nguni people of southern Africa, especially a Xhosa. 

  • A language spoken by the Nguni peoples of southern Africa, especially Xhosa. 

  • In Islamic contexts, a non-Muslim. 

How often have the words black man and kaffir occurred in a corpus of books? (source: Google Ngram Viewer )