carnet vs ducat

carnet

noun
  • An admission pass. 

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

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

ducat

noun
  • A ticket. 

  • A gold coin minted by various European nations. 

  • A coin of the major denomination (dollar, euro, etc.); money in general. 

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