calmness vs nonchalance

calmness

noun
  • The state of being calm; tranquillity; silence. 

  • The product of being calm. 

nonchalance

noun
  • Indifference, unconcern; carelessness; coolness; disregard, detachment. 

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