shopping center vs showroom

shopping center

noun
  • An area, either enclosed or unenclosed, hosting multiple retail establishments; a shopping mall. 

showroom

noun
  • A room in a business set aside for the display of the company's products. 

verb
  • To inspect merchandise in a physical store, then purchase the identical product from an online merchant; to use a physical store as a showroom for an online merchant. 

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