excretion vs going to the lavatory

excretion

noun
  • Something excreted in that manner, especially urine or feces. 

  • The process of removing or ejecting material that has no further utility, especially from the body; the act of excreting. 

going to the lavatory

How often have the words excretion and going to the lavatory occurred in a corpus of books? (source: Google Ngram Viewer )