I don't suppose the web (or the school on carefully casual enquiry) will tell you anything about the distribution of *actual* proficiency scores of kids going up? I don't think you should put too much weight on the minimum, at least not unless you know that there are regularly lots of children who only just make it (which might show up, for example, as significant numbers every year not making it, assuming some kind of continuity). The median could be very much higher.

Email: my username, followed by 2, at google's mail