How many years did it take the proportion of Southern Irish Protestants to decline from 10 to 3%?
return Southern Irish Protestants ;return the  proportion of #1 in  % ;return year when  #2 was  10 % ;return year when  #2 was  3 % ;return the  difference of #4 and  #3
['select', 'project', 'project', 'project', 'arithmetic']