Trying To Give Each Occurance An ID

Hi Guys, Ive been struggling to create a query, I wonder if anyone knew how to do this.

I have data setup basically like this: -

Code Customer
A CustA
A CustB
B CustC
C CustD
D CustH
D CustI
E CustE
F CustF
G CustG

Is there a way i can make a count work to show like this: -

Code ID Customer
A 1 CustA
A 2 CustB
B 1 CustC
C 1 CustD
D 1 CustH
D 2 CustI
E 1 CustE
F 1 CustF
G 1 CustG

So if there is more than one customer, the ID will accumulate until the code changes so it will revert back to one again.

Hope someone knows how to do this.

Thanks

Predator002