aplomb vs insouciance

aplomb

noun
  • Self-confidence; poise; composure. 

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

  • The perpendicular; perpendicularity. 

insouciance

noun
  • Carelessness, heedlessness, indifference, or casual unconcern. 

  • Nonchalance. 

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