Activity Monitor showing big data download...

Hi everyone

My activity monitor is showing data received at about 200 megs every time I use my macbook pro. All I have been doing is some light web browsing(not even you tube) and I don't know which application is doing this. I have software update switched off so its not that and the last installed software date was about five days ago with no new updates available.

Help with this one would be much appreciated as I am going through truckloads of data which is going 'nowhere"

Thanks in advance