globalpublicsquare.blogs.cnn.com — Editor's Note: Throughout the week, Ruchir Sharma will be posting thought-provoking questions with answers and explanations on CNN.com/GPS. Be sure to check out his excellent new book Breakout Nations: In Pursuit of the Next Economic Miracles. By Ruchir Sharma - Special to CNN Question: There are 15 members in the club of trillion-dollar economies.