affiliation vs pertinency

affiliation

noun
  • The relationship resulting from affiliating one thing with another. 

  • A club, society or umbrella organisation so formed, especially a trade union. 

  • The establishment of a child's paternity or maternity 

pertinency

noun
  • The quality of being pertinent to the matter at hand; relevance. 

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