@Override
    public String toString() {
        return "ZoneSnapshot [instanceCount=" + instanceCount
                + ", loadPerServer=" + loadPerServer + ", circuitTrippedCount="
                + circuitTrippedCount + ", activeRequestsCount="
                + activeRequestsCount + "]";
    }
Captures the metrics on a Per Zone basis (Zone is modeled after the Amazon Availability Zone)
@author awang
ribbon-loadbalancer/src/main/java/com/netflix/loadbalancer/ZoneSnapshot.java