Creating Directory - Showing Listing Count on All Directory Pages

Hi to all InDesign Scripters

I am currently creating a directory with InDesign CS6, which contains the name of the person, address, cities, etc.

I have a question which is about showing the listing count per city,

for example, there are 30 names under a city (across spreads and pages),

how to show the number of listing count on InDesign automatically?

And how to make InDesign pick up what numebrs to use on that page?

(If I have two pages should show total listing count under the same city is 30)

I found a script to add sequential # to the paragraph styles, however I was only able to pick up the last number on the page using text variable -Running Headers function in InDesign, not the last number under the same city.

Any help would be appreciated!

Best Regards

V