cop out vs weasel out

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. 

weasel out

verb
  • To shirk, avoid, or fail to fulfill (a task, responsibility, etc.) 

  • To obtain or extract, especially by cunning methods. 

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