public String toString(){
        StringBuilder sb = new StringBuilder();
        
        sb.append("[Server:" + server + ";");
        sb.append("\tZone:" + server.getZone() + ";");
        sb.append("\tTotal Requests:" + totalRequests + ";");
        sb.append("\tSuccessive connection failure:" + getSuccessiveConnectionFailureCount() + ";");
        if (isCircuitBreakerTripped()) {
            sb.append("\tBlackout until: " + new Date(getCircuitBreakerTimeout()) + ";");
        }
        sb.append("\tTotal blackout seconds:" + totalCircuitBreakerBlackOutPeriod.get() / 1000 + ";");
        sb.append("\tLast connection made:" + new Date(lastAccessedTimestamp) + ";");
        if (lastConnectionFailedTimestamp > 0) {
            sb.append("\tLast connection failure: " + new Date(lastConnectionFailedTimestamp)  + ";");
        }
        sb.append("\tFirst connection made: " + new Date(firstConnectionTimestamp)  + ";");
        sb.append("\tActive Connections:" + getMonitoredActiveRequestsCount()  + ";");
        sb.append("\ttotal failure count in last (" + failureCountSlidingWindowInterval + ") msecs:" + getFailureCount()  + ";");
        sb.append("\taverage resp time:" + getResponseTimeAvg()  + ";");
        sb.append("\t90 percentile resp time:" + getResponseTime90thPercentile()  + ";");
        sb.append("\t95 percentile resp time:" + getResponseTime95thPercentile()  + ";");
        sb.append("\tmin resp time:" + getResponseTimeMin()  + ";");
        sb.append("\tmax resp time:" + getResponseTimeMax()  + ";");
        sb.append("\tstddev resp time:" + getResponseTimeStdDev());
        sb.append("]\n");
        
        return sb.toString();
    }
Gets the 99.5-th percentile in the total amount of time spent handling a request, in milliseconds.
ribbon-loadbalancer/src/main/java/com/netflix/loadbalancer/ServerStats.java