centaur vs flying dragon

centaur

noun
  • A mythical beast having a horse's body with a man's head and torso in place of the head and neck of the horse. 

  • An icy planetoid that orbits the Sun between Jupiter and Neptune. 

  • A chess-playing team comprising a human player and a computer who work together. 

flying dragon

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

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

  • Any lizard in the genus Draco. 

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