apathy vs unconcern

apathy

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

unconcern

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

  • Freedom from worry or apprehensiveness; insouciance or nonchalance. 

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