mettle vs stupidity

mettle

adj
  • Spirited, vigorous, stout-hearted. 

noun
  • Good temperament and character. 

  • A quality of endurance and courage. 

stupidity

noun
  • An act that is stupid. 

  • The property of being stupid. 

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