air ticket vs carnet

air ticket

noun
  • A document issued at time of payment for an airfare, entitling the holder to travel. 

carnet

noun
  • A customs document that allows the temporary duty-free importation of a particular article 

  • An admission pass. 

  • A ticket book, a collection of tickets in the form of a booklet often sold at a discount to single tickets. 

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