doolally vs off one's head

doolally

adj
  • Eccentric; insane, mad. 

  • Carried away by enjoyment, excitement, etc. 

off one's head

prep
  • Insane, crazy. 

  • Temporarily mentally unstable; very distressed. 

  • Under the influence of drugs. 

How often have the words doolally and off one's head occurred in a corpus of books? (source: Google Ngram Viewer )