inexistence vs unconvincingness

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. 

unconvincingness

noun
  • The state or condition of being unconvincing. 

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