By how many percent lower was the unemployment rate in March 2016 compared to February 2012?
return unemployment rate ;return #1 in  March 2016 ;return #1 in  February 2012 ;return percent of #2 ;return percent of #3 ;return difference of #5 and  #4
['select', 'filter', 'filter', 'project', 'project', 'arithmetic']