gentlemen's room vs lavvy

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 

lavvy

noun
  • A lavatory: a room used for urination and defecation. 

  • A toilet: a fixture used for urination and defecation. 

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