ending vs unending

ending

noun
  • A termination or conclusion. 

  • The last part of something. 

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

unending

adj
  • Not ending; having no end; eternal. 

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