How to arrange array to display on chart (chart)

This chart is intended to list the total number of monthly accesses per user type for the current year.

It is divided into 3 series, each series represents a type of user, within it has the total of hits of that type per month:

labels: ['Jan', 'Fev', 'Mar', 'Abr', 'Mai', 'Jun', 'Jul', 'Ago', 'Set', 'Out', 'Nov', 'Dez'],
series: [
    [100, 200, 120, 280, 150, 300, 350, 200, 180, 350, 420, 500], // Total Access Users
    [80, 150, 100, 180, 80, 250, 150, 280, 360, 450, 520, 650], // Total artists
    [30, 80, 40, 90, 50, 100, 70, 160, 220, 240, 280, 350], // total studios
]

I tried the following:

    public function get_monthly_accesses() {

        $current_year = date('Y');
        $responseseries = array();
        for ($j = 1; $j <= 3; $j++) {

            for ($i = 1; $i <= 12; $i++) {
                $query = "select count(date_login) as accesses from user_access as ua
inner join user_details as ud on ud.user = ua.user
inner join user as u on ua.user = u.id
where type = {$j} AND YEAR(date_login) = {$current_year} AND MONTH(date_login) = {$i}";

                $total = $this->db->query($query)->result()[0]->accesses;
                $responseseries[] = $total;
            }

        }

        echo '<pre>';
        var_dump(json_encode($responseseries));
        echo '</pre>';
        die;

        return json_encode($responseseries);
    }

The return is this:

string(147) "["0","0","0","0","0","0","0","0","0","0","7","0","0","0","0","0","0","0","0","0","0","1","13","0","0","0","0","0","0","0","0","0","0","2","10","0"]"

I'm not able to split this array to 3 to display on the chart.