There's a simple explanation for this.
Due to a time-space anomoly, a bubble of slow time has formed around Fins room, causing everything inside this bubble to move normally while time itself is continuing normally outside of this bubble. Therefor it appears as though there are more people in other rooms than there are in Fins, when there are really less in the other rooms.
Another plausible theory is the room-pwning hippo. This hippo is completely invisible, and is only trackable using a hippo-detector. When this invisible hippo enters a room, it's massive hippo-ness wieghs the room down the list. Very logical.
Then there's the theory that flying raccoons have swarmed all the other rooms, making it appear as though there's more users.
Either that, or a good chunk of VMK's population consists of perverts. but whatever.