excretion vs expulsion

excretion

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

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

expulsion

noun
  • The act of expelling or the state of being expelled. 

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