public static function getRegionNames()
    {
        if (is_null(self::$regionNames)) {
            $GEOIP_REGION_NAME = array();
            require_once PIWIK_INCLUDE_PATH . '/libs/MaxMindGeoIP/geoipregionvars.php';
            self::$regionNames = $GEOIP_REGION_NAME;
        }

        return self::$regionNames;
    }