ending vs series finale

ending

noun
  • The last part of something. 

  • A termination or conclusion. 

  • The last morpheme of a word, added to some base to make an inflected form (such as -s in "dogs"). 

series finale

noun
  • The promotional or advertisement term used to describe the final episode of a television program, usually a situation comedy or a drama. 

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