ducat vs subpoena

ducat

noun
  • A ticket. 

  • A gold coin minted by various European nations. 

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

subpoena

verb
  • To summon with a subpoena. 

noun
  • A writ requiring a defendant to appear in court to answer a plaintiff's claim. 

  • A writ requiring someone to appear in court to give testimony. 

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