David Bardey University of Rosario and Toulouse School of Economics   Casa Pedro Fermín Calle 14 # 4 - 69 Bogotá, Cundinamarca Colombia   david.bardey@gmail.com   https://sites.google.com/site/davidbardey/           JEL Areas: I0 : Health, Education, and Welfare: General L1 : Market Structure, Firm Strategy, and Market Performance: General