drummer vs travelling salesman

drummer

noun
  • One who plays the drums. 

  • A drumstick (the lower part of a chicken or turkey leg). 

  • A housebreaker. 

  • Any of various fish of the family Kyphosidae, which make a drumming sound. 

travelling salesman

noun
  • A man who travels, often within a certain territory, soliciting orders or selling goods. 

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