gentlemen's room vs necessarium

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 

necessarium

noun
  • A lavatory. 

  • Synonym of reredorter: a monastery's latrine, outhouse, or lavatory, typically located behind the dormitory. 

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