inexistence vs unsoundness

inexistence

noun
  • The state of not being, not existing, or not being perceptible. 

  • The state of existing in something 

  • That which exists within; a constituent. 

unsoundness

noun
  • The state of being unsound. 

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