snitch vs stab in the back

snitch

verb
  • To inform on, especially in betrayal of others. 

  • To contact or cooperate with the police for any reason. 

noun
  • A ball used in the sport of Quidditch. 

  • A thief. 

  • An informer, one who betrays his group. 

  • A nose. 

  • A tiny morsel. 

stab in the back

verb
  • To betray (somebody). 

noun
  • An act of betrayal or treachery 

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