You can use Charon to determine what country the proxy is from. Anyone using proxies should have Charon.
The real question is to symbiotic and seodeveloping is, how many of your proxies are CODEEN and or PLANETLAB proxies? I am sick and tired of getting lists of 500 proxies, and 60% of them are codeen/planetlab proxies. Anyone into proxies knows these proxies are MONITORED and utterly useless unless you want to see a redirect page letting you know you are on the codeen network and your actions are being monitored. And any blackhat/hacking/cracking methods will be reported to the defensive site.
I have been into proxies for years. I can grab hundreds of fresh, good, filtered proxies a day. The range varies from 200 to about 800.
Good thing you added the password to your proxies to make them "private proxies" by definition. Even if the proxies are not posting to the scene, they are still scattered through VIP proxy boards, membership sites, and by proxy hunters like myself. Your proxy is not hidden nor off limits to me unless it is passworded. All you have to do is type a range into Charon, or ChickenProx, or whatever like 69.125.55.0 - 69.254.254.254 and if you have one of your "private proxies" in that range, I will find it and use it unless you have it password protected. NOTE: the range was for example, it can be whatever range you want to set, the wider the longer the scan will take.
No proxy is private unless it has a password. Without the password, it will be a matter of days and someone who scans ranges like I mentioned will find it.
I don't want to buy the service, as I have no trouble gathering my own proxies, but to help out the others who are interested, you want to ensure you aren't using codeen and/or planetlab proxies. (they were seperate and they merged, thats why you normally see it named "Codeen/PlanetLab". At least thats the story I got). I have a filterfile made for charon to remove almost all the codeen/pl proxies. No list will be 100%, but I never have had one yet in the last year.