confidence vs doubtfulness

confidence

noun
  • 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. 

  • Self-assurance. 

doubtfulness

noun
  • The state or quality of being doubtful; doubt; uncertainty. 

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