cowherd vs grazier

cowherd

noun
  • A person who herds cattle; a cowboy. 

grazier

noun
  • One who grazes cattle and/or sheep on a rural property. 

  • The owner of a large property on which sheep or cattle graze. 

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