Counting "own goals" as any goal where a defender is last to touch the ball and it wouldn't have gone into the goal otherwise is simple but it's just not useful. The skill is setting the defender in that impossible situation to begin with, and it's the attackers' effort that does it. It's filed together with true own goals which are mistakes - and it's silly.
"Proper" own goals where a normal goal isn't almost a given in the milliseconds after, are still extremely rare and always were.