imbecility vs witlessness

imbecility

noun
  • Something imbecilic; a stupid action, behaviour, etc. 

  • The quality of being imbecile; weakness; feebleness, especially of mind. 

witlessness

noun
  • The state of being witless; stupidity. 

How often have the words imbecility and witlessness occurred in a corpus of books? (source: Google Ngram Viewer )