courtship vs lick someone's boots

courtship

noun
  • The behaviour exhibited by an animal to attract a mate. 

  • The act of trying to solicit a favour or support from someone. 

  • The act of wooing a person to enter into a romantic relationship or marriage; hence, the period during which a couple fall in love before their marriage. 

lick someone's boots

verb
  • To try hard to please someone. 

How often have the words courtship and lick someone's boots occurred in a corpus of books? (source: Google Ngram Viewer )