commission agent vs sales clerk

commission agent

noun
  • A merchant earning a commission by selling goods belonging to others. 

  • An agent entrusted with the possession of goods to be sold in the agent's name. 

  • A person entrusted with a confidential task, often secretly to place a bet. 

sales clerk

noun
  • A person employed by a store to sell merchandise, assist customers in finding merchandise, and accept payment. 

How often have the words commission agent and sales clerk occurred in a corpus of books? (source: Google Ngram Viewer )