Member of Parliament vs senator

Member of Parliament

noun
  • A representative elected by the voters of an electoral district to a house of a parliament. 

senator

noun
  • A member, normally elected, in the house or chamber of a legislature called a senate, as, for instance, the legislatures of the United States and Canada. 

  • A member of the ruler’s council or governing council in general, a leading statesman. 

  • A member of the ancient Roman Senate. 

  • A member of a governing council in other states in the ancient world. 

How often have the words Member of Parliament and senator occurred in a corpus of books? (source: Google Ngram Viewer )