free pass vs immunity

free pass

noun
  • An exemption from normal processes. 

  • An intentional walk. 

  • A document entitling the bearer to free transportation. 

immunity

noun
  • An exemption from specified duties, such as payments or services. 

  • An exemption from penance. 

  • An exemption given to a player from losing or being withdrawn from play. 

  • A resistance to a specific thing. 

  • An exemption from prosecution. 

  • Protective resistance against disease. 

How often have the words free pass and immunity occurred in a corpus of books? (source: Google Ngram Viewer )