apologue vs work of fiction

apologue

noun
  • A short story with a moral, often involving talking animals or objects; a fable. 

  • The use of fable to persuade the audience. 

work of fiction

noun
  • A fictional account; a story. 

  • A fictitious account; an account of events that never took place. 

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