public static function getPercentage(array $tab, array $keys = null)
    {
        $plein = 0;
        $total = 0;
        foreach ($tab as $key => $value) {
            if (is_array($keys) && !in_array($key, $keys)) {
                continue;
            }
            if ($value) {
                $plein++;
            }
            $total++;
        }
        return floor(($plein / $total) * 100);
    }