aplomb vs unflappability

aplomb

noun
  • Self-confidence; poise; composure. 

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

  • The perpendicular; perpendicularity. 

unflappability

noun
  • The state of being unflappable. 

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