cop out vs run out on

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. 

run out on

verb
  • To leave a partner or commitment suddenly and without prior warning. 

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