get blood out of a stone vs whistle in the wind

get blood out of a stone

verb

  • To do something difficult, frustrating, or pointless. 

whistle in the wind

verb

  • To attempt something that is futile; to say something that is not heeded. 

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