little girls' room vs women's room

little girls' room

noun
  • Synonym of ladies' room: a public lavatory intended for use by women. 

  • A room belonging to or used by little girls, particularly their bedroom. 

women's room

noun
  • Synonym of ladies' room: a public lavatory intended for women. 

  • A waiting room in a railway station or other public building intended exclusively for women and usually including a separate women's lavatory. 

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