Survivor Counter

I am currently running Hell's Rebels from Pathfinder 1e. We are racing towards the end of Book 3 (spoilers ahead). At the end of this book the heroes find themselves trapped in a building and defending civilians from getting slaughtered. There are hundreds at the beginning of combat and the amount of survivors at the end plays a part in mechanics present in Book 4. I am Roll20 stupid, the most I've been able to do is make a couple of macros. What I would like is an on-screen counter that starts with the tally of citizens at the beginning and I can either roll dice to decrease the number or physically change the tally each round.  Bonuus points if I'm able to edit it to look cool and thematic. Any help would be greatly appreciated! - J

Without the api, the only thing I think you could use that you could adjust with a macro and have on screen would be the Turn Order with {&tracker:-} and the like. 

Thanks for the reply The, I'm probably going back to a premium membership before the Masquerade takes place. And would you mind pointing me in the direction of what you are referring to with the {&tracker:-} comment as I am lost. :)  - J