How can we calculate the percentage of 'distance' covered by the scrollbar on an element between start and end?

<div id=container style=overflow-x:scroll; max-width:1000px;>

  <div id=contained style=width:3000px;></div>

</div>



<script>

  $('#container').scroll(function(){

    var scrollPercentage; //How to get scroll percentage?

  });

</script>

So, if the scrollbar is completely at the left we want to get 0, and if it's completely at the right we want to get 100.