unconcern vs world-weariness

unconcern

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

  • Freedom from worry or apprehensiveness; insouciance or nonchalance. 

world-weariness

noun
  • The state or characteristic of being world-weary. 

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