What material is the B737 wing skin made out of?

What material is the B737 wing skin made out of?

I actually couldn’t find much information on the wing skin upper and lower panel materials for the B737, the general guess is of course aluminium, but I’m hoping to know specifically what series of aluminium?

The 2000 or the 7000 series? even within these, specifically which one like, Al 7068 or Al 2124?