lastScrollY=0;
function heartBeat(id){ 
var diffY;
if (document.documentElement && document.documentElement.scrollTop)
    diffY = document.documentElement.scrollTop;
else if (document.body)
    diffY = document.body.scrollTop
else
    {/*Netscape stuff*/}
    
//alert(diffY);
percent=.1*(diffY-lastScrollY); 
if(percent>0)percent=Math.ceil(percent); 
else percent=Math.floor(percent); 

lastScrollY=lastScrollY+percent; 
//alert(lastScrollY);
}