private function yearType($year)
    {
        $year_length = $this->yToJd($year + 1) - $this->yToJd($year);

        if ($year_length === 353 || $year_length === 383) {
            return self::DEFECTIVE_YEAR;
        } elseif ($year_length === 355 || $year_length === 385) {
            return self::COMPLETE_YEAR;
        } else {
            return self::REGULAR_YEAR;
        }
    }