The statistics are not valid as they are not adjusted for size of intake.
Raffles Girls Primary has an intake of over 300. Some schools have an intake of only 100.

Without some form of normalisation for intake size, this “school popularity index” (at best) is not in any way a proxy for “best”

Maybe if the analysis was based on the average PSLE score, or number of students admitted into an (arbitrary) “good school” like RGS