function displayBySeries() {
	Event.observe('go_btn', 'click', showHide, false);
}
			
function showHide() {
	var x = document.display_series.select_series;
	var series = x.options[x.selectedIndex].value;
	for (i=0;i<x.options.length;i++)
	//alert($(x.options[i].value).style);
		$(x.options[i].value).style.display = "none";
	if (series) $(series).style.display = "block"; 
}