get blood out of a stone vs push off

get blood out of a stone

verb
  • To do something difficult, frustrating, or pointless. 

push off

verb
  • To delay, postpone, put off, push back. 

  • To go away; to get lost. 

  • to commit a foul by pushing against an opponent to both accelerate more quickly and push the opponent in the opposite direction. 

How often have the words get blood out of a stone and push off occurred in a corpus of books? (source: Google Ngram Viewer )