private function _getItems()
    {
        $typesAvailable = ['fix', 'calculation'];

        $this->yearStart = intval($this->yearStart);
        $this->yearEnd = intval($this->yearEnd);

        if (!in_array($this->yearStartType, $typesAvailable)) throw new InvalidConfigException("The 'yearStartType' option is must be: 'fix' or 'calculation'.");
        if (!in_array($this->yearEndType, $typesAvailable)) throw new InvalidConfigException("The 'yearEndType' option is must be: 'fix' or 'calculation'.");

        if ($this->yearStartType == 'calculation') $this->yearStart += date('Y');
        if ($this->yearEndType == 'calculation') $this->yearEnd += date('Y');

        $yearsRange = range($this->yearStart, $this->yearEnd);

        return array_combine($yearsRange, $yearsRange);
    }