How many percent difference is there between the school with the highest number of students that did not gain an GCSE pass and the lowest?
return schools ;return students of #1 ;return #2 that did not  gain a GCSE pass ;return percents of #3 ;return the  highest of #4 ;return the  lowest of #4 ;return the  difference of #5 and  #6
['select', 'project', 'filter', 'project', 'aggregate', 'aggregate', 'arithmetic']