1. Demography Unit, Åbo Akademi University, Strandgatan 2, 65100 Vasa, Finland ().
2. Population Research Institute, 502 Oswald Tower, Pennsylvania State University, University Park, PA, 16802 USA ().
3. Norwegian National Advisory Unit on Ageing and Health, Vestfold Hospital Trust, Tønsberg, Norway; Department of Geriatric Medicine, Oslo University Hospital, Oslo, Norway; Columbia University, Oslo University Cracow School of Economics ().