ablutions vs sitz bath

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. 

sitz bath

noun
  • A hydrotherapeutic bath taken in a sitting position. 

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