john vs shit bowl

john

noun
  • A device or place to urinate and defecate: now usually a toilet or lavatory, but also (dated) a chamber pot or outhouse. 

  • A male mule. 

  • A Western man traveling in East Asia. 

  • A prostitute's client. 

shit bowl

noun
  • A bowl used for defecation: a chamber pot or toilet. 

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