equerry vs stable boy

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. 

stable boy

noun
  • A boy or young man who attends in a stable. 

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