secret ballot vs vote

secret ballot

noun
  • The voting system involving ballots available only at official polling places, prepared at public expense, containing the names of all candidates, and marked in secret at the polling places. 

vote

noun
  • an act or instance of participating in such a choice, e.g., by submitting a ballot 

  • a formalized choice on legally relevant measures such as employment or appointment to office or a proceeding about a legal dispute. 

  • any judgment of intellect leading not only to a formal opinion but also to a particular choice in a legally relevant measure, a point of view as published 

verb
  • to cast a vote; to assert a formalized choice in an election 

  • to choose or grant by means of a vote, or by general consent 

How often have the words secret ballot and vote occurred in a corpus of books? (source: Google Ngram Viewer )