It depends. Is your wifi locked down with a secure password, and you aren't using WEP, but at least WPA2?
Also did you see the status on your own computer, or via your router?
Most wireless routers allow you to check which computers are connected to it - it will give their IP address as well as their MAC address.
However - anyway you look at it, that's a lot of uploads, literally 10 to 1 upload to download ratio.