The director of our talent search said that historically the numbers stay very even from year to year. So one would not expect large shifts. I wouldn't worry about changes in %, especially if you started high. Say a kid gets 22 of 25 right in science (I'm just making this up) in 3rd grade. The next year, there isn't a lot of space to improve, but other kids will start to catch up, so your % will likely shift some. I am not facile with statistics, so not sure if this is accurate, but it makes sense to me.