Im 13 and my rating is around 620, but it's rising fast. Im guessing by the time I'm 14 I will have around 800 elo (which is in less than 4 months btw)
I love the fact that people are dropping uscf ratings so high they would be top 500 worldwide for their age. Personally I think that if you have a rating of 700 at 13 its average. Because I just broke the 1000 mark and I can get top 3 in most tournaments.