How many more people, in terms of percentage, belonged to the two smallest age groups combined compared to the largest age group?
return age  groups ;return percentages of #1 ;return the  two lowest of #2 ;return the  highest of #2 ;return sum of #3 ;return the  difference of #5 and  #4
['select', 'project', 'aggregate', 'aggregate', 'aggregate', 'arithmetic']