It's number sold, so it's not all pre-ordered, only those that shipped prior to today. When you pre-order, you are able to cancel up until it's shipped, and payment is not taken until it's shipped, so these numbers can't be counted.

Given that the white models sold out* within hours (or was it minutes?) and the entry level black model sold out the next day, subsequent orders would not be included in this figure.

* By sold out I mean shipping date slipped