chantage vs shakedown

chantage

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

shakedown

noun
  • Extortion, especially through blackmail 

  • A thorough search; a frisk 

  • A trial or test period, especially of a ship or aircraft 

  • An improvised bed. 

adj
  • that tests the performance of a ship or aircraft 

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