@panpacific, I’ve actually looked in to this (including looking at the matriculation lists of the most renown prep schools and magnets), and I don’t believe you can find a single HS in this country (that graduates more than 100 a class) that sends 1/3 of its class to the top 5.
Feel free to prove me wrong.
Even 1/3 of a class to Ivies/equivalents (and I’m including 30 schools in that category) is tough to do these days and something that only a handful of the most elite HS’s in this country consistently pull off.