It's entirely possible Nintendo has decided to start diverting some thousands of units per week away from Japan, because they feel they have the region secured and want to focus more on the other two. Europe and the US have both had enormous sales at almost 100k and 120k respectively the last few, so it certainly would make sense.
It does seem a pretty radical drop though, and I'm not sure I'd be doing anything similar if I was calling the shots at Nintendo. Must be a part of their world-domination master plan. =/







