What are the maximum, minimum and average home games each stadium held?
return stadiums ;return home games #1 held ;return number of  #2 for each  #1 ;return maximum of  #3 ;return minimum of  #3 ;return average of  #3 ;return #4 ,  #5 ,   #6
['select', 'project', 'group', 'aggregate', 'aggregate', 'aggregate', 'union']