men's room vs portajohn

men's room

noun
  • A lavatory intended for use by men, often including urinals in addition to toilets. 

  • Other rooms intended for use by men, as waiting rooms, dressing rooms, locker rooms, etc. 

portajohn

noun
  • A portable restroom. 

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