Could you check OOTB summary view, Work- . OpenCountByStatusForWorkPoolIC?
On the "Drill Down" tab there is an attribute to limit the records returned by drill down: 'Maximum number of rows to retrieve'. This is controlling the number of records returned in drill down reports. I have private edited this to limit number of rows to 5.
When I have run this summary view for my application work pool got couple of work statuses with counts more than 500. In drill down report it showed only 5 records with a message as shown in below image:
May be you can try this OOTB summary view and check if it satisfies your requirement.