extortion vs vampirism

extortion

noun
  • The practice of extorting money or other property by the use of force or threats. 

vampirism

noun
  • extortion 

  • practices associated with vampires, in particular blood-drinking and the draining of a victim's life-force. 

  • Systemic lupus erythematosus (autoimmune disease) 

  • the state of being a vampire 

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