do not, however, constitute administrative units and are mostly used for statistical and economic purposes. Land use The Swiss territory is divided into four major types of land use. , 36.9% of the land in Switzerland was used for farming. 30.8% of the country is covered with forests and woodlands, with an additional 6.8% covered with houses or buildings. About one-fourth (25.5%) of the country is either mountains, lakes or rivers and is categorised as unproductive. Surfaces of housing and infrastructure The habitat is mainly developed in the Swiss Plateau and the northern slopes of the Alps, near lakes and along major rivers. It occupies 14.6% of the Plateau, the Jura (7.4%), the southern (4.3%) and the northern Alps (4%), and finally the western central Alps (2.9%) and Eastern Alps (1.6%). Habitat areas and infrastructure grow around the urban areas but also in the countryside, at the expense of agricultural land. This growth (called suburbanization) is particularly pronounced along the main transport routes such as motorways and railways. New roads lead to a significant increase in construction activity in the affected regions. Many people who work in the city prefer to live in the countryside to take advantage of cheaper land and better quality of life. This is also reflected in the construction statistics: single-family homes arise mainly in rural areas, multi-family homes in the cities. Household structures are also evolving and tend to become smaller. In twelve years, the area devoted to housing increased by 25% while the increase of the population was only 9%. Farmland Although it is declining, agriculture represents the most important use of the territory in Switzerland. Farmlands dominates the Plateau, occupying just over half of the area. The situation is similar in the Jura (44%), on the northern slopes of the Alps (38.2%) and in the eastern Central Alps (31.4%). In the mountainous regions of the western Central Alps (Valais) and in the south, the agricultural areas (mostly pastures) are proportionately lower. In 1993 it was estimated that (or about 0.6%) of the entire country was irrigated meaning that most Swiss farms receive enough rainfall to grow. The protection of forested areas led to numerous conflicts of interests around the farmland, especially on the Plateau and near urban areas where the habitat area development and infrastructure tend to reduce the amount of arable land. Conversely, the number of farms in the mountains tend to