Probably a million of total ns shipments in Japan are exports!And why you should not erase it from the map yet.

[DekutheEvilClown]

If I understand correctly you are saying the gap in shipped to sold is because of units being exported, but I do not believe that is how that works. I believe those exported units would still be sold through normal retail channels(and therefore registered as sales through Famitsu etc.)and then exported. The exporting does not remove from the normal sales channel, unless something really dodgy is going on somewhere.