Missing KF

In my Model, I have to find out Nr of Docs Posted . This will be achieved by Counting the nr of documents where Document Status = Blank.

If I dont have a counter in my model, how can I achieve this in reports? Do I need to create a RKF / CKF/ Variable for this?

Also I need to calculated % nr of docs parked

for this I need to Find out Nr of Docs Parked (where BSTAT=V) and then (Nr of Documents Parked/Nr of Documents Posted )*100....Can any one tell me the solution

Thanks