cop out vs flee

cop out

verb
  • To avoid or shirk, either by failing to perform, or by performing in a grossly insufficient, negligent, or superficial manner. 

  • To plead guilty and ask for mercy. 

flee

verb
  • To disappear quickly; to vanish. 

  • To run away; to escape. 

  • To escape from. 

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