bathhouse vs natatorium

bathhouse

noun
  • A building where swimmers can change clothes. 

  • A business with bath-like facilities, which chiefly serves as a place for sexual encounters, especially among men. 

  • A building with baths for communal use. 

natatorium

noun
  • A swimming pool, especially an indoor one; a building housing one or more swimming pools. 

How often have the words bathhouse and natatorium occurred in a corpus of books? (source: Google Ngram Viewer )