carnet vs triptyque

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. 

triptyque

noun
  • A customs pass allowing a motor vehicle into and out of France. 

  • A triptych. 

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