Issue with Top Ten Postcode Widget

Hello,

I'm having a ticket count issue with my top ten postcode widget. When I have the ranking for the Primary Postcode filter set to top 10 the postcode of 45202 comes up with a ticket count of 403, but when I change the ranking to top 400 45202 now has a ticket count of 637. Any idea what might be causing this increase in the ticket count?