var bUp = 1;
function beoordeling(el) {
	if( bUp == 1 ) {
		el.style.background = 'url(images/beoordeling_down.png)'
		bUp = 0;
	}
	else {
		el.style.background = 'url(images/beoordeling_up.png)'
		bUp = 1;
	}
}