air force vs aviation

air force

noun
  • A branch of the military mainly devoted to air warfare, as opposed to (land) army and navy. 

  • A unit in the U.S. Air Force larger than a division but smaller than a command. 

aviation

noun
  • Flying, operating, or operation of aircraft. 

  • Industry that produces aircraft. 

  • A cocktail made with gin, maraschino liqueur, crème de violette and lemon juice 

  • The art or science of making and flying aircraft. 

  • aircraft 

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