cobra vs flying dragon

cobra

noun
  • Any of various venomous snakes of the family Elapidae. 

  • A type of lanyard knot, thought to resemble a snake in its shape. 

flying dragon

noun
  • Any lizard in the genus Draco. 

  • Draco volans, a gliding lizard endemic to Southeast Asia. 

  • Used other than figuratively or idiomatically: see flying, dragon. 

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