Extrapolating data over time

Hi,
I need to extrapolate data overtime.
Our company lifestreams music events. We partner with music producing organizations. Every new partner contributes a certain number of events per year. I am trying to work this out in excel. Can anyone help?
I'll explain more:
Year one; month one; first partner signs up. This partner contributes 6 events over 12 months. Over the whole of year one - we'll sign up 10 partners, each with the same number of contributed events over twelve month (from the signup date).
Help anyone?
thanks
Dan Shorer
CEO
u-sophia.com