nonpublic vs unofficial

nonpublic

adj
  • Not open to the public; not available to or shared by the public; private. 

unofficial

adj
  • Not officially established. 

  • Not acting with official authority. 

  • Implicitly true but withheld and/or contradicted by authority. 

  • Not listed in a national pharmacopeia etc. 

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