courtesanship vs rough trade

courtesanship

noun
  • The state of being a courtesan; harlotry. 

rough trade

noun
  • Rough or tough men, either gay or straight, who are available as casual sexual partners for other men (for example in exchange for money). 

  • Violent or sadomasochistic sex, especially casual gay sex. 

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