public void updatePercent(){
	pastPrices.add(price);
	if (pastPrices.size() > 300)
	    pastPrices.remove(); // remove oldest price after 300 passed
	double oldP = pastPrices.peek(); // oldest value in queue
	percentChange = ((price - oldP)/price) * 100;
	percentChange = (double)(Math.round(percentChange * 100)) / 100; // rounds to 10th
	if (percentChange == 0.0)
	    percentChange = 0.01; // little cheat to get around some errors
    }