Frankfurter vs joker

Frankfurter

noun
  • A native or inhabitant of Frankfurt, Germany. 

joker

noun
  • A jester. 

  • A funny person. 

  • An unspecified, vaguely disreputable person. 

  • A friendly unit that acts as a suspected hostile unit in a military excercise. 

  • A person who makes jokes. 

  • A clause in a contract that undermines its apparent provisions. 

  • A man. 

  • A playing card that features a picture of a joker (that is, a jester) and that may be used as a wild card in some card games. 

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