auctioneer vs travelling salesman

auctioneer

noun
  • A person who conducts an auction on behalf of a vendor, taking bids to find the best price for the vendor. 

verb
  • To sell at an auction; to auction. 

travelling salesman

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

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