Comment by nodesocket

Interesting, huge companies seem to only use the current year:

   © 2014 GitHub, Inc.
   © 2014 DigitalOcean ™ Inc.
   © 2014, Amazon Web Services, Inc. or its affiliates. All rights reserved.
   Facebook © 2014
   Copyright © 2014 Tesla Motors, Inc. All rights reserved.

We leads me to believe it does not matter.