chairman vs shop steward

chairman

noun
  • A person presiding over a meeting. 

  • 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. 

verb
  • To serve as chairman. 

shop steward

noun
  • A local member of a trade union elected to represent his fellow workers in discussions with the management at a workplace. 

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