oligarch vs rex

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. 

rex

noun
  • An animal which has a genetic recessive variation that causes the guard hairs to be very short or fully lacking. 

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