mitigation vs moderation

mitigation

noun
  • A reduction or decrease of something harmful or unpleasant. 

moderation

noun
  • An instance of moderating: bringing something away from extremes, especially in a beneficial way 

  • The state or quality of being moderate; avoidance of extremes 

  • The process of moderating a discussion 

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