Martin Bizimana Kyungpook National University   Dept. of Econ, Kyungpook Nat'l Univ. 80 Daehak-ro, Buk-gu Daegu, Daegu 41566 South Korea   martinbizimana1@gmail.com             JEL Areas: O4 : Economic Growth and Aggregate Productivity: General J1 : Demographic Economics: General