cohabit vs refrain

cohabit

verb
  • To live together with someone else, especially in a romantic and sexual relationship but without being married. 

  • To coexist in common environs with. 

refrain

noun
  • The chorus or burden of a song repeated at the end of each verse or stanza. 

  • A much repeated comment, complaint, or saying. 

verb
  • To stop oneself from some action or interference; to abstain. 

  • To abstain from (food or drink). 

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