Do Websites Go On Vacation?

It's well known that websites have traffic patterns and that there are those times of the day/week/month/year were traffic predictably increases or decreases. Just like the 405 in LA, or the LIE in New York, or the 75/85 connector in Atlanta, traffic is likely to be pretty light at 2:00am on a Sunday, but travel those same roads 30 hours later and, well, bring a book...

Its easy to understand the ebbs and flows that individual sites may have, but I recently I noticed something a little strange in Drupal's usage data that leads me to ask: why would an entire framework/CMS (we can leave the existential "what is Drupal?" question out of this) have similarly predictable patterns. This is the usage graph as of January 12, 2013:

What struck me is the dip that seems to happen every December around the holidays. Sure, lots of people go on vacation or hit the eggnog pretty hard and so they are spending less time on their favorite websites, but these sites still exist, right? No body ever gets up from there desk once December arrives and declares: "OK folks, its almost Christmas. Pack up our site for a couple weeks and we'll spin that baby back up after New Years." Even less likely is the bloggers that decide to switch to Joomla just for the eight days of Chanukah. 

So what gives?

Maybe this happens with all CMS/frameworks or maybe this is a unique phenomenon to Drupal but in either case, the mystery persists. So I leave you with this question: Do websites go on vacation?