Why does my preloader start at 40%?

programming flash
1

The code to my knowledge is fine, I just dont know why it doesnt show the progress bar and percentage at the beggining, Starts at like 40% loaded.

Below is my code

stop();

myInterval = setInterval(preload,100);

function preload() {
    var current = _root.getBytesLoaded();
    var total = _root.getBytesTotal();
    var pctLoaded = Math.round(current/total*100);
    pct_txt.text = pctLoaded+"%";
    loaderBar_mc._xscale = pctLoaded;
    
    if (current >= total) {
        gotoAndStop(2);
        clearInterval(myInterval);
    }
}