gayness vs heterosexuality

gayness

noun
  • The state of being gay (homosexual); 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. 

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