Superman Returns was PG-13. The Reeve movies (I through IV) were all PG. It does seem like there's fewer and fewer G rated movies (for that matter, PG), though. I can't think of a SINGLE movie off to top of my head that wasn't less than a PG or PG-13 that I've seen and even fewer rated G.

CLARK: No. I'm just worried I'm a jinx.
JONATHAN: A jinx?
CLARK: Yeah. Let's face it, ever since she's known me, Lois's been kidnapped, frozen, pushed off buildings, almost stabbed, poisoned, buried alive and who knows what else, and it's all because of me.
-"Contact" (You're not her jinx, you're her blessing.)