/**
  * Get the Mean of all the stats that are watched, for all the stats added with add() between
  * the latest call to clear() and now (in JSON).
  *
  * @return The Mean of all the stats since last clear() in JSON.
  */
 public String getMeanJSON() {
   String str =
       String.format(
           FakeUserStats.jsonMediaStreamStatsTemplate,
           -1, // ssrc not needed here
           downloadJitterMs.getMean(),
           downloadPercentLoss.getMean(),
           downloadRateKiloBitPerSec.getMean(),
           jitterBufferDelayMs.getMean(),
           jitterBufferDelayPackets.getMean(),
           nbDiscarded.getMean(),
           nbDiscardedFull.getMean(),
           nbDiscardedLate.getMean(),
           nbDiscardedReset.getMean(),
           nbDiscardedShrink.getMean(),
           nbFec.getMean(),
           nbPackets.getMean(),
           nbPacketsLost.getMean(),
           nbReceivedBytes.getMean(),
           nbSentBytes.getMean(),
           packetQueueCountPackets.getMean(),
           packetQueueSize.getMean(),
           percentDiscarded.getMean(),
           rttMs.getMean(),
           uploadJitterMs.getMean(),
           uploadPercentLoss.getMean(),
           uploadRateKiloBitPerSec.getMean());
   return str;
 }