calmness vs sangfroid

calmness

noun
  • The product of being calm. 

  • The state of being calm; tranquillity; silence. 

sangfroid

noun
  • Composure, self-possession or imperturbability especially when in a dangerous situation. 

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