Say I have a report that looks like this in preview:

a
a
b
b
b
d
d
e
f
f
g,

where the data is grouped as shown.  I would like to have running counts placed after the list, like so:

a
a
b
b
b
d
d
e
f
f
g

a: 2
b: 3
c: 0
d: 2
e: 1
f: 2
g: 1.

Is there an easy way to do this, other than to create a running total for each individual letter (a,b,c,...,g)? 

Furthermore, supposing that 'c' is a possible value in the data that isn't being selected, how can I create the running totals so that any total with a value of 0 does not show up (in the above case, "c: 0" would not show up)?

Any and all help is greatly appreciated.  Thanks!!