nark vs snitch up

nark

verb
  • To serve or behave as a spy or informer. 

  • To stop. 

  • To annoy or irritate. 

  • To complain. 

  • To watch; to observe. 

noun
  • An unpleasant person, especially one who makes things difficult for others. 

  • A police spy or informer. 

snitch up

verb
  • To come forward and snitch on someone. 

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