Raymundo M Campos-vazquez El Colegio de Mexico   Carretera Picacho Ajusco 20 Col. Ampliacion Fuentes del Pedregal Mexico City, DF 14110 Mexico   rmcampos@colmex.mx   http://cee.colmex.mx/raymundo-campos           JEL Areas: J3 : Wages, Compensation, and Labor Costs: General D3 : Distribution: General