Friar Minor vs greyfriar

Friar Minor

noun

  • Synonym of Franciscan: a member of the Order of the Friars Minor. 

greyfriar

noun

  • Synonym of Franciscan: a member of the Order of the Friars Minor. 

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