Return the average, maximum, and minimum budgets in millions for movies made before the year 2000.
return movies ;return years made of  #1 ;return #1 where #2 is  before 2000 ;return budgets in millions of  #3 ;return average of  #4 ;return maximum of  #4 ;return minimum of  #4 ;return #5 ,  #6 ,   #7
['select', 'project', 'comparative', 'project', 'aggregate', 'aggregate', 'aggregate', 'union']