If I'm not mistaken the max block size is 1MB and there are an expected 144 blocks a day. Meaning you shouldn't see more than 144 MB per day. Unless I completely misunderstand nodes it should just be receiving and sending that per day. Your total output I'm not sure what it be. The total output should be no more than 144MB x total connections to your node - 1 (your incoming data had to come from at least one of your connections, so they already have it).