bisexuality vs heterosexuality

bisexuality

noun
  • The state of being sexually or romantically attracted to members of either sex or gender. 

  • The state of being bisexual (“having both male and female parts or roles”). 

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 bisexuality and heterosexuality occurred in a corpus of books? (source: Google Ngram Viewer )