oligarchy vs the ragtag (and bobtail)

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. 

the ragtag (and bobtail)

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