coach driver vs teamster

coach driver

noun
  • A person driving a horse-drawn coach (carriage). 

  • A person employed to drive a coach (long-distance bus). 

teamster

noun
  • A person who drives a team of animals (such as horses or oxen). 

  • A person who drives a cargo truck (see Teamster). 

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