cast about vs leave no stone unturned

cast about

verb
  • To try to find; look around; search. 

  • To plan; plot; contrive. 

leave no stone unturned

verb
  • To search or investigate thoroughly. 

  • To perform a task carefully and thoroughly, not missing any step. 

How often have the words cast about and leave no stone unturned occurred in a corpus of books? (source: Google Ngram Viewer )