I have done this in a slightly different way, using and agent to evaluate a view. I created a field on each form called Reportflag. I then created an agent to go through each form and evaluate whether the form should be included in a view or not. In your case checking to see if the used is a memeber of the readers field or not. If the form should be included in a view the Reportflag is set to 1, otherwise the flag is set to 0.
You can then create a view that shows only forms where the reportflag is set to 1.
You can then run the agent from the view and it will only report valid documents. The totals should work then.
If you have any trouble let me know.