nonchalance vs urbanity

nonchalance

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

urbanity

noun
  • Behaviour that is polished, refined, courteous. 

  • Urbanness. 

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