Timer metric

{
"count": (number) events recorded for this metric,
"total": (number) sum of the durations of events recorded for this metric,
"mean_rate": (number) average rate,
"m1_rate": (number) one-minute average rate,
"m5_rate": (number) five-minute average rate,
"m15_rate": (number) fifteen-minute average rate,
"mean": (number) total/count, or 0 if count is 0,
"min": (number) minimum duration recorded,
"max": (number) maximum duration recorded,
"stddev": (number) standard deviation of recorded durations,
"p50": (number) 50% at or below this value,
"p75": (number) 75% at or below this value,
"p95": (number) 95% at or below this value,
"p98": (number) 98% at or below this value,
"p99": (number) 99% at or below this value,
"p999": (number) 99.9% at or below this value,
"p9999": (number) 99.99% at or below this value,
"p99999": (number) 99.999% at or below this value
}