What is the maximum, minimum, and average amount of money outsanding for all customers?
return customers ;return money outsanding of #1 ;return amounts of #2 ;return maximum of #3 ;return minimum of #3 ;return average of #3 ;return #4 , #5 ,  #6
['select', 'project', 'project', 'aggregate', 'aggregate', 'aggregate', 'union']