develop vs hit pay dirt

develop

verb
  • To progress through a sequence of stages. 

  • To bring out images latent in photographic film. 

  • To advance; to further; to promote the growth of. 

  • To acquire something usually over a period of time. 

  • To place one's pieces actively. 

  • To change with a specific direction, progress. 

  • To create. 

  • To cause a ball to become more open and available to be played on later. Usually by moving it away from the cushion, or by opening a pack. 

  • To change the form of (an algebraic expression, etc.) by executing certain indicated operations without changing the value. 

hit pay dirt

How often have the words develop and hit pay dirt occurred in a corpus of books? (source: Google Ngram Viewer )