code: private float getMapAvarageProgress(int tasksPerBar, int index
        , TaskReport[] reports ) {
      float progress = 0f;
      int k=0;
      for(;k < tasksPerBar && index + k < reports.length; k++) { 
        progress += reports[index + k].getProgress();
      }
      progress /= k;
      return progress;
    }
docs: Computes average progress per bar