var now = (new Date()).getTime();
var validBanners = new Array();
var j = 0;

for (i=0; i<banners.length; i++) {
	if (banners[i][0] == 'NL' && banners[i][1] <= now && banners[i][2] >= now) {
		validBanners[j] = banners[i];
		j++;
	}
}

var randomNumber = Math.floor(Math.random()*validBanners.length);
var currentBanner = validBanners[randomNumber];