commoner vs earl

commoner

noun
  • A member of the common people who holds no title or rank. 

  • Someone who has a right over another's land. They hold common rights because of residence or land ownership in a particular manor, especially rights on common land. eg: centuries-old grazing rights 

  • Someone who is not of noble rank. 

earl

noun
  • A British or Irish nobleman next in rank above a viscount and below a marquess; equivalent to a European count. A female using the style is termed a countess. 

  • Any of various nymphalid butterflies of the genus Tanaecia. Other butterflies in this genus are called counts and viscounts. 

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