earl vs landowner

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. 

landowner

noun
  • A person who owns land. 

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