equerry vs stableman

equerry

noun
  • An officer responsible for the care and supervision of the horses of a person of rank. 

  • A personal attendant to a head of state, a member of a royal family, or a national representative. 

stableman

noun
  • A person employed to take care of horses in a stable. 

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