rsync using huge traffic

[Ben Oswald]

Hey,

I'm using rsync to backup my server but there is a problem because
rsync is using very huge amounts traffic. But first to the setup. The
server I backup has 4GB of data and I use the following command to
backup this data.  /usr/bin/rsync -aze 'ssh -i /root/.ssh/backup.key -l
backupuser' --rsync-path='sudo rsync' --delete --exclude-from=ex.list
$SRC $TRG 

The problem is that the traffic generated to backup these 4GB of data
is often (yes not every time I backup) up to 200GB and more if I don't
stop the process. Rsync it self is showing me not more than 4GB of
transmitted data at the end of the rsync call.
So is there a known reason for this behaviour of rsync and if yes how
can I solve this problem?

Best regards,

Ben