hammer-headed vs not the sharpest knife in the drawer

hammer-headed

adj

  • Having a head in the shape of a hammer 

  • stupid, ignorant 

not the sharpest knife in the drawer

noun

  • Lacking in intelligence; dimwitted. 

How often have the words hammer-headed and not the sharpest knife in the drawer occurred in a corpus of books? (source: Google Ngram Viewer )