commoner vs oligarch

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. 

oligarch

noun
  • A member of an oligarchy; someone who is part of a small group that runs a country. 

  • A very wealthy business owner who wields political power. 

  • A protoplanet formed during oligarchic accretion. 

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