coexistence vs pairing

coexistence

noun
  • The state of two or more things existing together, usually in a temporal or spatial sense, with or without mutual interaction. 

pairing

noun
  • The combination or union of two things. 

  • An agreement between two members of a legislative body holding opposite opinions to refrain from voting, so that both may absent themselves. 

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