I have noticed that nobody appears to have mentioned this report from IPTS (the prospective lab of the European Commission).
Here it is:
Pan-European survey of practices, attitudes and policy preferences as regards personal identity data management
Authors: W. Lusoli, M. Bacigalupo, F. Lupiañez, N. Andrade, S. Monteleone, I. Maghiros
[4 June 2012]