Can you remember whether it has his date of birth or just his age?
Alas, I can't; it was the info sheet Shen Wei lovingly stared at in episode 1 or 2, if that helps?

I think I'm sticking with my headcanon on this one. *pokes out tongue at art department*
I support your choice! :P I have my own headcanons, too, like Shen Wei only being woken up for ~14 years, despite that dude saying he'd been sent on a mission by the Black-Robed Envoy 20 years ago.