potency vs world power

potency

noun
  • Power, authority. 

  • Concentration; strength 

  • Sexual virility: the ability to become erect or achieve orgasm. 

  • Potentiality, ability, capacity. 

  • The ability or capacity to perform something 

world power

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

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