For those that land on this question even 9 years after it was posted, to see the request rate in real time and on a graph:

Open Performance Monitor, click Performance Monitor, then click the green + icon. On the list on the top left, scroll until you see Web Service, then click Total Method Requests/sec. Click Add >> to move it to the added counters list, then click OK. Other graphs will show on there, but you can hide them.

To change the amount of time shown on the graph, right-click it, click Properties... and click General. Change the duration (max: sample rate * 1000) to how long you like, and maybe the sample rate if the duration exceeds the limit.

It will not automatically save, so you will have to go back and add it every time.