carelessness vs unconcern

carelessness

noun
  • Lack of care; the state or quality of being careless. 

unconcern

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

  • Freedom from worry or apprehensiveness; insouciance or nonchalance. 

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