faeces vs feces

faeces

noun
  • UK, Canada, Ireland, South Africa, Australia, and New Zealand standard spelling of feces. 

feces

noun
  • Digested waste material (typically solid or semi-solid) discharged from a human or mammal's stomach to the intestines; excrement. 

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