kaffir vs wench

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. 

wench

noun
  • A black woman (of any age), especially if in a condition of servitude. 

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