irreflective vs unconcerned

irreflective

adj
  • Without mental reflection. 

unconcerned

adj
  • Indifferent and having no interest; aloof. 

  • Not anxious, apprehensive, or worried. 

  • Having no involvement. 

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