Frankfurter vs gangster

Frankfurter

noun
  • A native or inhabitant of Frankfurt, Germany. 

gangster

noun
  • A member of a professional criminal organization; a racketeer. 

  • A member of a criminal or street gang. 

verb
  • To act like a gangster; to commit street crime or run a racket. 

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