Proxies priority algorithm

I have a service using proxies. Service do a lot of requests over them. I have a task which every 10 minutes checks proxies. But proxies often fall down for several requests and after that them revive. So I did a pretty simple solution that summarize count of falls down during one hour. And I use this property like priority. It means that service get only alive proxy with higher priority. (With less count of falls down)

So my question: is there an "special" algorithm to make this process more "smart"? Smart priority for proxies?