Madonna vs Mother of Mercy

Madonna

name

  • The Virgin Mary, the mother of Jesus. 

  • A female given name from Italian. 

noun

  • An artistic representation of the Virgin Mary, chiefly when holding the infant Jesus. 

  • A morally pure woman. 

Mother of Mercy

name

  • The Virgin Mary, the mother of Christ. 

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