republic vs world power

republic

noun
  • A state where sovereignty rests with the people or their representatives, rather than with a monarch or emperor; a country with no monarchy. 

  • One of the subdivisions constituting Russia. See oblast. 

world power

noun
  • A nation or state so powerful that it can influence world affairs. 

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