Measure bps on a interface

Hi,

I have a router where I measure the min/max/average bps in/out on an Interface. This is on a 100mbps line and it seems that the bandwidth is nearly full on the Charts.

But is'nt the 100mbps line 100 in both direction ? So I have plenty of bandwidth available. Are there any other ways to construcy the graph.

Please see Attached Picture.

John