On his results: http://qph.is.quoracdn.net/main-qimg-7563466e4810af140bb712b...
Now this data distribution looks suspect to tampering. I will not pass judgements though without knowing the format of the papers. Besides, we do not know if indeed he actually fetched data for all the students and did not miss anybody, since he is relying upon his manual boundaries while scraping data. How informed are those boundaries is not known. ICSE schools are not normal run of the mill schools, they are populated by rich kids who can afford extra help and are kind of smart. Their English curriculum is reputed to be strong, hence the strong distribution towards high end. I am also making assumptions, but I do not have full data to make informed inferences.