conjugal vs matrimonial

conjugal

adj
  • Of or relating to marriage, or the relationship of spouses; connubial. 

matrimonial

adj
  • Of, or having to do with matrimony and marriage. 

noun
  • A classified advertisement describing an individual who wishes to find a marriage partner. 

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