[PHP] 몇 주년 계산하기

$debutDatetime = "2019-12-13 00:00:00";

$debutTime = (new DateTime($debutDatetime))->format("ymd");
$recentTime = (new DateTime())->format("ymd");

$yearDiff = (int)(((int)$recentTime - (int)$debutTime) / 10000);
$dateDiff = (int)(((int)$recentTime - (int)$debutTime) % 10000);