Sir vs king of kings

Sir

noun

  • The titular prefix given to a knight or baronet. 

king of kings

noun

  • A king who has other kings as subjects; an emperor. 

name

  • Jesus Christ. 

  • The title of an individual king who has other kings as subjects; in particular 

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