_per_msg" : {               (json object)
      "msg" : n,                          (numeric) The total bytes sent aggregated by message type
                                          When a message type is not listed in this json object, the bytes sent are 0.
                                          Only known message types can appear as keys in the object.
      ...
    },
    "bytesrecv_per_msg" : {               (json object)
      "msg" : n,                          (numeric) The total bytes received 