nonchalance vs uncertainty

nonchalance

noun
  • Indifference, unconcern; carelessness; coolness; disregard, detachment. 

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 nonchalance and uncertainty occurred in a corpus of books? (source: Google Ngram Viewer )