apathy vs insouciance

apathy

noun
  • Lack of emotion or motivation; lack of interest or enthusiasm towards something; disinterest (in something). 

insouciance

noun
  • Carelessness, heedlessness, indifference, or casual unconcern. 

  • Nonchalance. 

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