belligerence vs unkindness

belligerence

noun
  • The state of being belligerent; aggressive inclination to war. 

unkindness

noun
  • The state or quality of being unkind. 

  • An unkind act. 

  • The collective noun for ravens 

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