protected int getElementCoverage(Class<? extends Element> elementClass) {
		if (elementClass == null)
			throw new IllegalArgumentException("The given arguments are invalid!");
		
		int count = 0;

		for (Element e : grid.getElementsOnGrid())
			if (e.getClass() == elementClass || elementClass.isAssignableFrom(e.getClass()))
				count++;

		return (count * 100 / grid.gridSize());
	}