cash in one's chips vs pay the debt of nature

cash in one's chips

verb
  • To die. 

  • To discontinue an activity, accepting whatever gains or losses one has incurred; to give up. 

pay the debt of nature

verb
  • To die. 

How often have the words cash in one's chips and pay the debt of nature occurred in a corpus of books? (source: Google Ngram Viewer )