Ok, here an example:
This is the graph that shows message counts for the last 48 hours. The graph shows that last night around midnight the server processed (sent and received) less than 2000 messages. Also, it shows that today around noon, the server processed between 4K and 6K messages. There is a catch though, if you are using 4.0, these graphs are most likely broken. They are fixed in 4.5