mulish vs unsettled

mulish

adj
  • Characteristic of a mule; stubborn, obstinate, or intractable 

unsettled

adj
  • Unpaid. 

  • Not populated, having no settlers or other inhabitants. 

  • Disturbed, upset. 

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

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