unascertained vs unsettled

unascertained

adj
  • Not ascertained; undetermined; unknown. 

unsettled

adj
  • Not in a steady condition, uncertain, subject to change. 

  • Unpaid. 

  • Not populated, having no settlers or other inhabitants. 

  • Disturbed, upset. 

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