angst vs unhappiness

angst

noun
  • Emotional turmoil; painful sadness. 

  • A feeling of acute but vague anxiety or apprehension often accompanied by depression, especially philosophical anxiety. 

verb
  • To suffer angst; to fret. 

unhappiness

noun
  • The feeling of not being happy 

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