doubtfulness vs uncertainty

doubtfulness

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

uncertainty

noun
  • Doubt; the condition of being uncertain or without conviction. 

  • A parameter that measures the dispersion of a range of measured values. 

  • Something uncertain or ambiguous. 

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