Rotating an object with the mouse and retrieving data

Hi,

I'd like to be able to rotate an object using my mouse and then I need to know how quickly that object is rotating... I'm stumped!

In the picture the blue dotted circle will be the collision area where the player has to hold before spinning and the red dot in the middle is the pivot point.

The main trouble I'm having is figuring out a way to see how fast the player is rotating in code. I thought of looking for how many times the object rotates past a certain point in a certain time, but that wouldn't work if the player only did half a turn or something.

I'm sorry if it's hard to understand, I'm finding it hard to explain! Thanks.