Ah!
Switch numbers are entirely supply-dependant. I wonder if Nintendo had enough to reach the usual 40-50k level.
They seem to have been able to supply that sort of number consistently in the past, I doubt that much has changed - indeed, the recent 70k figures might be a sign of a ramp-up in production reaching the marketplace (or it could also be a sign of a reallocation of extra to Japan for GW)