anguish vs unhappiness

anguish

noun

  • Extreme pain, either of body or mind; excruciating distress. 

verb

  • To cause to suffer pain. 

  • To suffer pain. 

unhappiness

noun

  • The feeling of not being happy 

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