disappointment vs mirthfulness

disappointment

noun
  • An example or the act of disappointing: a circumstance in which a positive expectation is not achieved. 

  • The feeling or state of being disappointed: a feeling of sadness or frustration when something is not as good as one hoped or expected, or when something bad unexpectedly happens. 

  • Something or someone that disappoints: that which causes disappointment. 

mirthfulness

noun
  • The property of being mirthful; happiness 

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