1. Department of Statistics and Informatics, RIVM. National Institute for Public Health and the Environment (RIVM). Antonie van Leeuwenhoeklaan 9 3721 MA Bilthoven The Netherlands
2. Centre for Infectious Disease Control, RIVM. National Institute for Public Health and the Environment (RIVM). Antonie van Leeuwenhoeklaan 9 3721 MA Bilthoven The Netherlands