Is there a way to tell the age of an adult banded gecko?

[Rune]

I've had this little fellow for a few years now. I got him from some acquaintances whose kids had gotten bored of their pet, and they didn't seem to know much about him at all, they thought he was a leopard gecko, for starters. From my internet research, I'm fairly certain he's a western banded gecko.
Anyway, I'm hoping there's something I can look for that'll let me guess how old he is.

 

[acpart]

Once it's an adult there's no way to tell the age. It would be nice to see a picture in any event.

Aliza