godsend vs gold rush

godsend

noun
  • An unexpected good fortune or benefit; a windfall. 

gold rush

noun
  • A feverish obsession with seeking profits, especially in new markets. 

  • Any period of feverish migration into an area in which gold has been discovered. 

  • A cocktail made from bourbon, honey, and lemon juice. 

  • The urge to win gold medals, as in the Olympic Games. 

How often have the words godsend and gold rush occurred in a corpus of books? (source: Google Ngram Viewer )