function toggleTrace(theImage){
	var table = theImage.nextSibling.nextSibling.nextSibling.nextSibling;

	if(table.style.display == 'table'){
		table.style.display = 'none';
		theImage.src = 'gfx/plus.png';
	} else {
		table.style.display = 'table';
		theImage.src = 'gfx/minus.png';
	}
}