controversy vs strife

controversy

noun
  • A debate or discussion of opposing opinions; (generally) strife. 

strife

noun
  • Bitter conflict, sometimes violent. 

  • A trouble of any kind. 

  • Striving; earnest endeavor; hard work. 

  • Exertion or contention for superiority, either by physical or intellectual means. 

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