Oh! I thought the claim was that there was an error in the blue-grey box somewhere, and I was feeling dumb for not seeing it. Then I finally read the sentence

Oh! I thought the claim was that there was an error in the blue-grey box somewhere, and I was feeling dumb for not seeing it. Then I finally read the sentence at the end about the Gates Foundation, and I understood. :) Aside: based on the percentages, it looks like there were 85 schools per decile, or 850 schools total (give or take a few); in which case the total percentages indicate that a total of 58 or 59 distinct schools made it onto the Top 25 over a four-year period (23 of them from the smallest-decile schools). So there really is a lot of variability in the winners. I'd be interested to see a similar decile breakdown of schools that managed to get in the top 25 for at least two of the four years studied. That would seriously damp the noise.