extremism vs moderation

extremism

noun
  • Extreme ideas or actions, primarily in politics or religion. 

moderation

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

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

  • The process of moderating a discussion 

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