straphanger vs teamster

straphanger

noun
  • A person who travels using public transportation (often standing up and holding on to a strap). 

teamster

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

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

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