cruelty vs oligarchy

cruelty

noun
  • An indifference to suffering or pleasure in inflicting suffering. 

  • A cruel act. 

oligarchy

noun
  • Those who make up an oligarchic government. 

  • A state ruled by such a government. 

  • A government run by only a few, often the wealthy. 

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