3P vs troilism

3P

noun

  • threesome 

troilism

noun

  • The practice of three people having sex, i.e. having threesomes. 

  • The practice of two people having sex while a third person watches (and may or may not take part). 

How often have the words 3P and troilism occurred in a corpus of books? (source: Google Ngram Viewer )