How many more field goals did Stover kick in the first half than in the second half?
return Stover ;return field goals of #1 ;return #2 in  the  first half  ;return #2 in  the  second half  ;return the  number of  #3 ;return the  number of  #4 ;return the  difference of #5 and  #6
['select', 'project', 'filter', 'filter', 'aggregate', 'aggregate', 'arithmetic']