I don't have group data on that, just anecdotes. I'd guess more than 0.1 %, though. I do know that Brookline is among the systems that actually has a protocol (or did at the time) for early admission to kindergarten, heavily weighted toward the cognitive assessment. (WPPSI and WJ achievement, at the time.) And that some kids were able to get gifted pullout in elementary on the basis of an interview, history, and observation, without testing. Of course, it's been a few years, so things could have changed.
