The results are a bit better than what you'd expect though. In 2008, we had 4 99.95s - scores which are given to the top 0.05% of the state, or rather, 1/2000 students. Using the logic presented above, you'd expect that we'd had 8,000 students sit the entrance exam. In reality, it was more like 1,500, or even less.
Of course the students that sit the examination are more intelligent than the average, but you can't attribute statistics like that solely to the calibre of the cohort (especially seeing as we usually only have around 10 or so students per year level in the top 1% in various competitions). I'd agree that lots of the teachers are what you'd find anywhere (however, in saying that, some are absolutely astounding!), but I think the students do well because the academic environment is much more enriching. It's not seeing where your abilities are, per se, but admiring those of others and collectively benefiting from one another. That's what I've found.