aplomb vs level-headedness

aplomb

noun
  • Self-confidence; poise; composure. 

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

  • The perpendicular; perpendicularity. 

level-headedness

noun
  • The property of being level-headed. 

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