It seems like a lot of the 'end of year' stuff is happening a little earlier, and Nintendo is pitching in by launching its rather neat 'Year in Review' website.
If you go to the official page while logged into your Nintendo Account it summarises your play activity and breaks it down into all sorts of stats. You can see how many games you played, how many were 'new', and of course your most played games in terms of hours. You also get a percentage showing your docked / portable split, for example.
There are some interesting details; this scribe's 'busiest month' was October, for obvious reasons.
Be sure to check it out and share some of your stats in the comments!