public static function loadData() {
		if(static::$arrDBCalendar === null) {
			$years = \Database::getInstance()->prepare("SELECT * FROM tl_schoolyear")->execute();
			while($arrSY = $years->fetchAssoc()) {
				static::$arrDBCalendar[$arrSY['id']] = $arrSY;
			}
			$holidays = \Database::getInstance()->prepare("SELECT * FROM tl_schoolyear_holiday")->execute();
			while($arrHD = $holidays->fetchAssoc()) {
				static::$arrDBCalendar[$arrHD['pid']]['holidays'][$arrHD['id']] = $arrHD;
			}
		}
		return true;
	}