1. Lower Saxony Institute for Economic Research (NIW), Koenigstrasse 53, 30175 Hannover, Germany
2. Department of Applied Economics, Erasmus University Rotterdam, PO Box 1738, NL-3000 Rotterdam, The Netherlands, and Tinbergen Institute, Rotterdam, Netherlands
3. Department of Applied Economics, Erasmus University Rotterdam, PO Box 1738, NL-3000 Rotterdam, The Netherlands, and Tinbergen Institute, and Erasmus Research Institute of Management, Netherlands