The specific numbers for each school are listed below, which show 6.9% black, making the 8% black on athletic teams OVER-represented compared to the student body. The CDS, IPEDS, and College Navigator all match the percentages below (when comparing the same years), which all differ from your numbers. I’ve ordered from largest to smallest student population.
Cornell – 6.3% (15k students)
Penn – 7.3% (10k students)
Columbia – 7.5% (8k students)
Harvard – 7.1% (7k students)
Brown – 6.5% (7k students)
Yale – 6.8% (5k students)
Princeton --7.6% (5k students)
Dartmouth – 6.7% (4k students)
I’m not sure why you keep focusing on this slight difference in the overall average, rather than the huge differences in specific sports. The 2 sports that usually get the biggest admission boost both average more than 20% black across the Ivy League – that’s huge compared to the ~7% black student body. While sports like sailing, skiing, and equestrian only have 1 black student across all 3 sports among the entire Ivy League. Black students are essentially non-existent on many teams. When different teams have such huge differences in terms of both ethnic diversity and admission advantages, it’s not appropriate to emphasize the overall average and ignore specific teams.