confidence vs imperturbability

confidence

noun
  • Self-assurance. 

  • A feeling of certainty; firm trust or belief; faith. 

  • Information held in secret; a piece of information shared but to thence be kept in secret. 

imperturbability

noun
  • A state of calm, unruffled self-assurance; aplomb, composure. 

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