diploma vs power of attorney

diploma

noun
  • A document issued by an educational institution testifying that the recipient has earned a degree or has successfully completed a particular course of study. 

power of attorney

noun
  • A legal document allowing one person to act as the agent of another. 

  • The legal authorisation of one person to act as the agent of another. 

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