code: public String statistics() {
          DecimalFormat formatter = new DecimalFormat("#,###");
          DecimalFormat floatFormatter = new DecimalFormat("#,###.00");
          return String.format("min %s | avg %s | max %s | stddev %s msgs",
                  formatter.format(minRate()), formatter.format(avgRate()),
                  formatter.format(maxRate()), floatFormatter.format(stdDev()));
      }
docs: Formats the statistics for this group in a human-readable format.
  
  @return the statistics for this group in a human-readable format (string)