general election vs referendum

general election

noun
  • An election, usually held at regular intervals, in which candidates are elected in all or most constituencies or electoral districts of a nation. 

  • An erection. 

referendum

noun
  • A direct popular vote on a proposed law or constitutional amendment. The adposition on is usually used before the related subject of the vote. 

  • An action, choice, etc., which is perceived as passing judgment on another matter. 

How often have the words general election and referendum occurred in a corpus of books? (source: Google Ngram Viewer )