Yes they say that they will have 50-55 spots for new students in Grade 6 vs 40-45 in Grade 9. That is a ~60% jump in enrollment in Grade 6 and ~20% in Grade 9. I used the enrollment data by grade available at the NCES private school lookup website earlier and it matched pretty well. Where it is a struggle to estimate is the smaller schools such as the Girls-only schools. E.g. just looking at Brearley enrollment in Grade 5 vs Grade 6 it seemed like there were only ~5 new spots but that assumes no attrition. I believe actual spots for new students in Grade 6 last year were higher about 8-9.