ablutions vs natatorium

ablutions

noun
  • The location or building where the showers and basins are located. 

  • A building that houses bathing and toilet facilities on a military base. 

natatorium

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

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