function yearArray() {
	var currentDate = new Date();
	var currentYear = currentDate.getFullYear();
	var minYear = currentYear;
	var latestYear = 1990;
	
	var years = new Array();
	for(i=currentYear;i>latestYear;i--) {
		if (document.getElementById('title_' + i)) {
			if (minYear > i) {
				minYear = i;}}}
	return minYear;}

function changeYear(direction) {
	var currentDate = new Date();
	var currentYear = currentDate.getFullYear();
	var minYear = yearArray();
	var currentDisplay = document.getElementById('display_year').innerHTML;
	if (direction == 'earlier') {
		var nextDisplay = parseInt(currentDisplay) - 1;}
	if (direction == 'later') {
		var nextDisplay = parseInt(currentDisplay) + 1;}
	if (nextDisplay > currentYear) {
		nextDisplay = currentYear;}
	if (nextDisplay < minYear) {
		nextDisplay = minYear;}
	if (nextDisplay == currentYear) {
		document.getElementById('later').className = 'scroll_link';}
	else {
		document.getElementById('later').className = 'scroll_link clickable';}
	if (nextDisplay == minYear) {
		document.getElementById('earlier').className = 'scroll_link';}
	else {
		document.getElementById('earlier').className = 'scroll_link clickable';}
	document.getElementById('display_year').innerHTML = nextDisplay;
	document.getElementById('title_'+currentDisplay).className = 'hidden';
	document.getElementById('title_'+nextDisplay).className = 'display';}