How many more percent of low birth weight babies were born to smokers than non-smokers?
return babies ;return #1 that were low birth weight ;return #2 that were born to smokers ;return #2 that were born to non-smokers ;return percent of #3 ;return percent of #4 ;return difference of #5 and  #6
['select', 'filter', 'filter', 'filter', 'project', 'project', 'arithmetic']