cop out vs welsh

cop out

verb
  • To plead guilty and ask for mercy. 

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

welsh

verb
  • To go back on one's word. 

  • To cheat or swindle someone, often by not paying a debt, especially a gambling debt. 

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