[1] Stockholm Univ, Inst Int Econ Studies, S-10691 Stockholm, Sweden
[2] Ctr Econ Policy Res, London EC1V 0DG, England
[3] Univ Southampton, Southampton, Hants, England
[4] Univ Pompeu Fabra, Barcelona, Spain
[5] Univ Edinburgh, Edinburgh, Midlothian, Scotland
[6] Hebrew Univ Jerusalem, Jerusalem, Israel