firman vs rain check

firman

noun
  • A royal decree issued by a sovereign in certain historical Islamic states, especially by the Sultan of Turkey. 

rain check

noun
  • to make good on any experience that the customer deems unsatisfactory. 

  • A reissue, at no extra charge, of a ticket for a baseball game or other outdoor event postponed or interrupted because of rain. 

  • In social interactions, a deferred invitation, or deferred acceptance of an invitation. 

  • to provide a sold-out item or temporarily unavailable service at a later date for the running (usually special) price. 

How often have the words firman and rain check occurred in a corpus of books? (source: Google Ngram Viewer )