haggler vs travelling salesman

haggler

noun
  • A person who buys vegetables and other produce from farms and then sells them on in a different location; a person who transports farm goods. 

  • A person who haggles. 

travelling salesman

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

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