heterosexuality vs homosexuality

heterosexuality

noun
  • The state of being sexually and romantically attracted primarily or exclusively to persons of the opposite sex. 

  • Sexual activity with a person of the opposite sex. 

homosexuality

noun
  • The state of being sexually attracted primarily or exclusively to persons of the same sex, sometimes (potentially offensive) restricted to same-sex attraction between males. 

  • Sexual activity with a person of the same sex, sometimes (potentially offensive) restricted to same-sex sex between males. 

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