[1] Univ Gothenburg, Vasagatan 1,Box 640, S-40530 Gothenburg, Sweden
[2] Univ Antonio Nebrija, Madrid, Spain
[3] ETH, Ctr Econ Res, Zurich, Switzerland
[4] Grad Inst, Chemin Eugene Rigot 2A, CH-1211 Geneva, Switzerland
[5] Bogazici Univ, Natuk Birkan Binasi, Dept Econ, 2 Kat, TR-34342 Istanbul, Turkey