public Object clone() throws CloneNotSupportedException {
    	HistogramDataset clone = (HistogramDataset) super.clone();
        int seriesCount = getSeriesCount();
    	clone.list = new java.util.ArrayList(seriesCount);
        for (int i = 0; i < seriesCount; i++) {
        	clone.list.add(new HashMap((Map) this.list.get(i)));
        }
    	return clone;