dunny vs house of office

dunny

noun
  • Any other place or fixture used for urination and defecation: a latrine; a lavatory; a toilet. 

adj
  • Somewhat deaf, hard of hearing. 

  • Slow to answer: stupid, unintelligent. 

  • Somewhat dun, dusky brownish. 

house of office

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