var startValue = 0;
var startDate = new Date(2009, 02, 01);
var perDay = 1732 / 365.25;

function roundNumber(num, dec) 
{
    var result = Math.round(num*Math.pow(10,dec))/Math.pow(10,dec);
    return result;
}

function runCounter()
{
    var today = new Date();
    document.getElementById("counter").innerHTML = roundNumber(startValue + ((today.getTime() - startDate.getTime()) / (1000*60*60*24)) * perDay, 4) + "";
    setTimeout("runCounter()", 1000);
}