The exact amount is difficult to measure. It will depend on how many players are in your area of concern. If you really are having to count bytes.
Open the "Local Area Connection" in the Network Sharing panel, jet before you launch the game, taking care to make sure all other applications are disabled, and Microsoft updates are disabled as well.
In the "Local Area Connection Status" panel it will show you the number of bytes sent and received. Note the numbers and launch the game. Play for a period of time, in normal play conditions for you, then exit the game and note the new counts in the status panel.
That should give you an idea of how much data activity there is on your connection.