docs: @Override
      public double average()
      {
          readLock.lock();
          try
          {
              double s = 0;
              PrimitiveIterator.OfInt it = modIterator();
              while (it.hasNext())
              {
                  s += ring[it.nextInt()];
              }
              return s/(count());
          }
          finally
          {
              readLock.unlock();
          }
      }