butler vs houseboy

butler

noun
  • A valet, a male personal attendant. 

  • The chief male servant of a household who has charge of other employees, receives guests, directs the serving of meals, and performs various personal services. 

  • A manservant having charge of wines and liquors. 

verb
  • To buttle, to dispense wines or liquors; to take the place of a butler. 

houseboy

noun
  • A non-white adult male domestic servant. 

  • A young male domestic servant, especially in a British colony in former times. 

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