sheepdog vs stockman

sheepdog

noun
  • A breed of dog used for guarding sheep. 

  • A breed of dog, used for herding sheep. 

  • A police officer. 

verb
  • To chaperon or shepherd. 

stockman

noun
  • A man who raises or looks after livestock. 

  • A person who works in a stockroom. 

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