If I release my website in Dec 2015, the copyright date should definitely say "© 2015". Once Jan 1st comes around, if I automatically (with Javascript or some server side code) change it to "© 2016" is that legal? No code has changed, so there is nothing that is really copyright 2016.

I tried searching for an answer, but everything I found was about how to change automatically, not if it was OK to do so.