cash cow vs golden goose

cash cow

noun
  • A product, service, or enterprise that generates ongoing, high net free cash flows. 

  • Someone or something which is a dependable source of appreciable amounts of money. 

golden goose

noun
  • Something that generates much profit or gives great advantages. 

How often have the words cash cow and golden goose occurred in a corpus of books? (source: Google Ngram Viewer )