Division by Zero error (PHP set cookie issue)

Question

My php raty script structure is as follows and it keeps showing "division by zero". It seems that input result can not be written into the Mysql database.

Should I change something in "$aver = $rs['total'] / $rs['voter']; ? Many Thanks!

original script as follows

include_once ('connect.php');
$score = $_POST['score'];
if (isset ($score)) {
$cookiestr = getip();
$time = time();
if (isset ($_COOKIE['person']) && $_COOKIE['person'] == $cookiestr) {
    echo "1";
}
elseif (isset ($_COOKIE['rate_time']) && ($time -intval($_COOKIE['rate_time'])) < 60) {
    echo "2";
    } else {
    $query = mysql_query("update raty set voter=voter+1,total=total+'$score' ");
    $query = mysql_query("select * from raty");
    $rs = mysql_fetch_array($query);
    $aver = $rs['total'] / $rs['voter'];
    $aver = round($aver, 1) * 10;
    // set COOKIE
    setcookie("person", $cookiestr, time() + 3600 * 365);
    setcookie("rate_time", time(), time() + 3600 * 365);
    echo $aver;
}
}

function getip() {
if (getenv("HTTP_CLIENT_IP") && strcasecmp(getenv("HTTP_CLIENT_IP"), "unknown")) {
    $ip = getenv("HTTP_CLIENT_IP");
} else
    if (getenv("HTTP_X_FORWARDED_FOR") && strcasecmp(getenv("HTTP_X_FORWARDED_FOR"), "unknown")) {
        $ip = getenv("HTTP_X_FORWARDED_FOR");
    } else
        if (getenv("REMOTE_ADDR") && strcasecmp(getenv("REMOTE_ADDR"), "unknown")) {
            $ip = getenv("REMOTE_ADDR");
        } else
            if (isset ($_SERVER['REMOTE_ADDR']) && $_SERVER['REMOTE_ADDR'] && strcasecmp($_SERVER['REMOTE_ADDR'], "unknown")) {
                $ip = $_SERVER['REMOTE_ADDR'];
            } else {
                $ip = "unknown";
            }
return ($ip);
}
?>

Answer 1

$aver = ($rs['voter'] == 0) ? 0 : $rs['total'] / $rs['voter'];