gentlemen's room vs public convenience

gentlemen's room

noun
  • A waiting room in a railway station or other public building, often including a separate lavatory. 

  • Any room intended for use by men 

public convenience

noun
  • A lavatory that is provided for public use, i.e. use by any person. 

How often have the words gentlemen's room and public convenience occurred in a corpus of books? (source: Google Ngram Viewer )