window.onload = function(){
	createTab();
	hideHeading();
	showCategory('year2007');
	setTabClick('year2007nav','year2007');
	setTabClick('year2006nav','year2006');
	setTabClick('year2005nav','year2005');
	setTabClick('year2004nav','year2004');
	setTabClick('year2003nav','year2003');
	setTabClick('year2002nav','year2002');
	setTabClick('year2001nav','year2001');
	setTabClick('year2000nav','year2000');
};

function hide(elementId) {
	document.getElementById(elementId).style.display = "none";
}
function show(elementId) {
	document.getElementById(elementId).style.display = "block";
}
function hideHeading() {
	hide('year2007');
	hide('year2006');
	hide('year2005');
	hide('year2004');
	hide('year2003');
	hide('year2002');
	hide('year2001');
	hide('year2000');
}
function showCategory(categoryName){
	hide('year2007'); 
	hide('year2006'); 
	hide('year2005'); 
	hide('year2004'); 
	hide('year2003'); 
	hide('year2002'); 
	hide('year2001'); 
	hide('year2000'); 
	show(categoryName);
	changeTab(categoryName);
}

function createTab() {
	var aboutcontent_footer = document.getElementById("aboutcontent_footer");
	var aboutcontent = document.getElementById("aboutcontent");
	var nav = document.createElement("ul");
	nav.setAttribute('id','historynav');
	nav.appendChild(createListItem('year2007nav','#year2007',"'07"));
	nav.appendChild(createListItem('year2006nav','#year2006',"'06"));
	nav.appendChild(createListItem('year2005nav','#year2005',"'05"));
	nav.appendChild(createListItem('year2004nav','#year2004',"'04"));
	nav.appendChild(createListItem('year2003nav','#year2003',"'03"));
	nav.appendChild(createListItem('year2002nav','#year2002',"'02"));
	nav.appendChild(createListItem('year2001nav','#year2001',"'01"));
	nav.appendChild(createListItem('year2000nav','#year2000',"'99-'00"));		
	aboutcontent_footer.insertBefore(nav,aboutcontent);
}
function createListItem(id,href,text) {
	var li = document.createElement("li");
	var a = document.createElement("a");
	var t = document.createTextNode(text);
	li.setAttribute('id',id);
	a.setAttribute('href',href);
	a.appendChild(t);
	li.appendChild(a);
	return li;
}

function setTabClick(listName,categoryName) {
	var e = document.getElementById(listName).getElementsByTagName('a')[0];
	e.onclick = function(){
		showCategory(categoryName);
		return false;
	};
}

function changeTab(categoryName){
	var e = document.getElementById('historynav');
	e.className = categoryName;
}