coolness vs unconcern

coolness

noun
  • Indifference; lack of passion or interest. 

  • The state of being cool, i.e. calm. 

  • The state of being cool, i.e. good or pleasing. 

  • The result or product of being cool, i.e. good or pleasing. 

  • The state of being cool, i.e. chilly. 

  • The result or product of being cool, i.e. chilly. 

unconcern

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

  • Freedom from worry or apprehensiveness; insouciance or nonchalance. 

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