coolheadedness vs serenity

coolheadedness

noun
  • The state or characteristic of being coolheaded. 

serenity

noun
  • The state of being serene; calmness; peacefulness. 

  • A lack of agitation or disturbance. 

  • A title given to a reigning prince or similar dignitary. 

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