Switzerland's population was being counted on Tuesday in what may be the country's last ever census. The massive exercise, carried out every 10 years, has drawn criticism over costs and the issue of data protection.
Everyone living in Switzerland on Tuesday, December 5, is required to complete the census.
For the first time, Swiss citizens have the option of filing their details on the Internet. The federal office for statistics said that by Monday 160,000 people - corresponding to 65,000 households - had availed themselves of the new service.
More than 12 million forms in the four national languages have been sent by post to some 94 per cent of the country's residents. The remainder, chiefly those living in small communities, are being visited by traditional enumerators, going from door to door.
Apart from the standard personal and career details, Swiss residents are being asked how much housework and other unpaid work they do, as well as how long it takes them to get to work, and which means of transport they use. They are also asked which language they think in.
Significantly, most residents are likely to find that some of their census forms have already been partly filled out with information provided by the local authorities.
The fact that much of the necessary information is already in the hands of the authorities has raised questions about the value of the exercise, and whether it justifies the SFr150 million ($87 million) cost - the most expensive census yet.
But Werner Haug, who is organising the census, told swissinfo that it is important for the authorities to gain as complete a picture as possible on the make-up of the population and how it is changing.
"There has been a lot of immigration, and the linguistic and religious structure of the population, especially in the big cities, has changed quite a lot. There are also the effects of structural changes in the economy, with new jobs and new professions."
He adds that although basic information is known about most Swiss residents, the data is incomplete. "We are investing in the development of these registers, especially the dwelling and building registers, but also registers of population, because they are non-existent or badly harmonised in Switzerland."
Another criticism, voiced by the Association of Data Protection Ombudsmen, concerns safeguards about personal data. For the first time, a private company - Data Care - is to participate in the collection and processing of information.
This has led to worries that private details about consumers could fall into the hands of Data Care's owners, which include Swiss Post and Germany's biggest media group, Bertelsmann.
Haug dismissed such fears as groundless. He said Data Care's staff is bound by the same confidentiality rules as the federal statistics office, and that the company cannot afford to any breach of confidence or its reputation would suffer.
The 2000 census may be the last ever. Haug said there are plans to make the collection of data a continuous process, and to supplement future censuses with representative surveys.
"Moving away entirely from such a big exercise is one of the possible scenarios. Putting together all the data available at one moment in time will always be necessary, but the data collection methods will certainly change very much."