Running Total excel stat sheet

Hello i am wanting to know how i would go about making a running total stat graph.
Basically what i need is this:
I work a certain amount hour, in that period i need to get say 7 stats per hour.
So if i start at 3:00pm and work til 4:00pm i need to be on 7 stats.
So if i am on 7 at this time, the graph would show:


This is what i mean

http://img179.imageshack.us/img179/5829/statsos.jpg

Basically it calculates what stats you should have based off your start time/end time,
Every time you click on a new order it record the time.



How would this work?
Thanks

Basically i want a REPT function that does this,
Where once you reach a certain amount of stats it changes color and goes up as shown above,