chairman vs chief minister

chairman

noun
  • The head of a corporate or governmental board of directors, a committee, or other formal entity. 

  • Someone whose job is to carry people in a portable chair, sedan chair, or similar conveyance. 

  • A person presiding over a meeting. 

verb
  • To serve as chairman. 

chief minister

noun
  • The leader of government in many semi-autonomous and constituent federal states. 

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