oligarch vs rajah

oligarch

noun
  • A very wealthy business owner who wields political power. 

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

  • A protoplanet formed during oligarchic accretion. 

rajah

noun
  • a Hindu prince or ruler in India. 

  • Any of various nymphalid butterflies of the genus Charaxes. 

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