exemption vs get-out-of-jail-free card

exemption

noun
  • The state of being exempt; immunity. 

  • Freedom from a defect or weakness. 

  • An act of exempting. 

  • A deduction from the normal amount of taxes. 

get-out-of-jail-free card

How often have the words exemption and get-out-of-jail-free card occurred in a corpus of books? (source: Google Ngram Viewer )