var navIdx=0;
					var navOns=new Array("hist_1900nav_on.gif","hist_1910nav_on.gif","hist_1920nav_on.gif","hist_1930nav_on.gif","hist_1940nav_on.gif","hist_1950nav_on.gif","hist_1960nav_on.gif","hist_1970nav_on.gif","hist_1980nav_on.gif","hist_1990nav_on.gif","hist_2000nav_on.gif");
					var navOffs=new Array("hist_1900nav_off.gif","hist_1910nav_off.gif","hist_1920nav_off.gif","hist_1930nav_off.gif","hist_1940nav_off.gif","hist_1950nav_off.gif","hist_1960nav_off.gif","hist_1970nav_off.gif","hist_1980nav_off.gif","hist_1990nav_off.gif","hist_2000nav_off.gif");
					var navIds=new Array("nav1900","nav1910","nav1920","nav1930","nav1940","nav1950","nav1960","nav1970","nav1980","nav1990","nav2000");
					var imgtagIds=new Array("img1900","img1910","img1920","img1930","img1940","img1950","img1960","img1970","img1980","img1990","img2000");
					var textIds=new Array("txt1900","txt1910","txt1920","txt1930","txt1940","txt1950","txt1960","txt1970","txt1980","txt1990","txt2000");
					var altTags=new Array("1900","1910","1920","1930","1940","1950","1960","1970","1980","1990","2000");
					var banners=new Array("hist_1900banner.jpg","hist_1910banner.jpg","hist_1920banner.jpg","hist_1930banner.jpg","hist_1940banner.jpg","hist_1950banner.jpg","hist_1960banner.jpg","hist_1970banner.jpg","hist_1980banner.jpg","hist_1990banner.jpg","hist_2000banner.jpg");
					
					
					function navOff(idx){
					//build img tag
					var imgStr="<a href=\"javascript:writeNav(";
					imgStr+=idx;
					imgStr+=")\" onmouseout=\"MM_swapImgRestore()\" onmouseover=\"MM_swapImage('";
					imgStr+=imgtagIds[idx];
					imgStr+="','','graphics/images/about/";
					imgStr+=navOns[idx];
					imgStr+="',1)\"><img src=\"/graphics/images/about/";
					imgStr+=navOffs[idx];
					imgStr+="\" alt=\"";
					imgStr+=altTags[idx];
					imgStr+="\" name=\"";
					imgStr+=imgtagIds[idx];
					imgStr+="\" id=\"";
					imgStr+=imgtagIds[idx];
					imgStr+="\" /></a>";
					
					
					// write html
					var divRef=MM_findObj(navIds[idx]);
					divRef.innerHTML=imgStr;
					
					}
					
					function navOn(idx){
					//build img tag
					var imgStr="<img src=\"/graphics/images/about/";
					imgStr+=navOns[idx];
					imgStr+="\" alt=\"";
					imgStr+=altTags[idx];
					imgStr+="\" />";
					
					// write html
					var divRef=MM_findObj(navIds[idx]);
					divRef.innerHTML=imgStr;
					}
					
					function textOff(idx){
					var divRef=MM_findObj(textIds[idx]);
					divRef.style.display="none";
					}
					
					function textOn(idx){
					var divRef=MM_findObj(textIds[idx]);
					divRef.style.display="block";
					}
					
					function bannerSwap(idx){
					var newImg="/graphics/images/about/";
					newImg+=banners[idx];
					var divRef=MM_findObj('histbanner');
					if(divRef!=null){divRef.src=newImg;}
					}
					
					function writeNav(newIdx){
					// set new index if arrows were clicked
					if(newIdx=="prev"){
						newIdx=navIdx;
						if(newIdx>0){
							newIdx--;
						}else{
							newIdx=(navIds.length-1)
						}
					}else if(newIdx=="next"){
						newIdx=navIdx;
						if(newIdx<(navIds.length-1)){
							newIdx++;
						}else{
							newIdx=0;
						}
					}
					// turn off old button
					navOff(navIdx);
					// turn on new button
					navOn(newIdx);
					// turn off old text
					textOff(navIdx);
					// turn on new text
					textOn(newIdx);
					// swap banner
					bannerSwap(newIdx);
					// set nav index to new index
					navIdx=newIdx;
					}