stoicism vs unconcern

stoicism

noun
  • A real or pretended indifference to pleasure or pain; insensibility; impassiveness. 

  • A school of philosophy popularized during the Roman Empire that emphasized reason as a means of understanding the natural state of things, or logos, and as a means of freeing oneself from emotional distress. 

unconcern

noun
  • Lack of interest or care; indifference or apathy. 

  • Freedom from worry or apprehensiveness; insouciance or nonchalance. 

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