pay-off vs protection money

pay-off

noun
  • A payment. 

  • A reward. 

  • A bribe. 

  • A resolution or justification of an event that has already occurred, especially in fiction. 

protection money

noun
  • Money paid, especially at regular intervals, to criminals or to corrupt officials who threaten to cause harm to the payer or to his or her business if the money is not paid. 

How often have the words pay-off and protection money occurred in a corpus of books? (source: Google Ngram Viewer )