public long getMeasuredZoneHits(String zone) {
        if (zone == null) {
            return 0;
        }
        zone = zone.toLowerCase();
        long count = 0;
        List<? extends Server> currentList = upServerListZoneMap.get(zone);
        if (currentList == null) {
            return 0;
        }
        for (Server server: currentList) {
            ServerStats stat = getSingleServerStat(server);
            count += stat.getMeasuredRequestsCount();
        }
        return count;
    }
This is the core function to get zone stats. All stats are reported to avoid
going over the list again for a different stat.

@param servers
ribbon-loadbalancer/src/main/java/com/netflix/loadbalancer/LoadBalancerStats.java