tactlessness vs thoughtlessness

tactlessness

noun
  • The result or product of being tactless. 

  • The state or quality of being tactless. 

thoughtlessness

noun
  • heedless disregard for the consequences of one's actions 

  • disregard for other's feelings 

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