1. Econometric Institute; Erasmus School of Economics; Erasmus University Rotterdam; P.O. Box 1738 3000 DR Rotterdam The Netherlands
2. Department of Industrial Engineering & Innovation Sciences; Eindhoven University of Technology; P.O. Box 513 5600 MB Eindhoven The Netherlands
3. National Institute for Public Health and the Environment (RIVM); P.O. Box 1 3720 BA Bilthoven The Netherlands