chantage vs slush fund

chantage

noun
  • blackmail; the extortion of money by threats of scandalous revelations 

slush fund

noun
  • Money stored for illegal or dishonest purposes. 

  • Money that has not been hypothecated or dedicated to a particular purpose, or which is used for a different purpose than originally intended. 

How often have the words chantage and slush fund occurred in a corpus of books? (source: Google Ngram Viewer )