gentlemen's room vs smallest room

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 

smallest room

noun
  • The lavatory: the room intended for urination and defecation. 

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