aplomb vs nonchalance

aplomb

noun
  • Self-confidence; poise; composure. 

  • The apparent elegance and precision exhibited by a confident, accomplished dancer. 

  • The perpendicular; perpendicularity. 

nonchalance

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

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