Nearly a quarter of the Balearic coast line has been developed, according to a new report from the tourism ministry. The islands have a total of 1'239 kilometres of coast line, and 275 kilometres have been built up, representing 22.2 per cent of the total. The report also says that 84 per cent of the building has taken place over the past 45 years. Before the tourist boom, only 43.3 kilometres of coast was built up and this corresponded to the sea fronts of coastal villages. But from 1956, when only 3.5 per cent of the coastline was built up, building started to boom, and the coastline was developed at the rate of about five kilometres a year. The report was compiled by the tourism ministry's Centre of Tourism Research and Technology (CITTIB), which has divided the coast into five types: beach, pebble beach, structural cliffs, marine cliffs and tiered coast. The development has been considerable in all categories but especially in those classifed as tiered and sandy beaches. Building in these two categories has been in the region of 31 per cent since 1956 compared to 21 per cent in marine cliffs. Building has increased by eight and five per cent respectively in pebble beaches and structural cliffs. The category which has attracted the most building is that of the beaches, which have been developed to the extent of 32 per cent. As to the use of the physical space of the beaches in themselves, Playa de Palma and the Playa de Alcudia support 6.8 million visitors between them during the summer months. According to the report, the ten main beaches of the Balearics are Arenal-Playa de Palma, Es Trenc, Cala Agulla, Mondrago, Playa de Alcudia, Son Bou, Arenal de Son Saura, Sa Vall d'Algaierens and Benirràs. Between them, they attract 10 million visitors in the summer, 6.8 million opting for Playa de Palma and Alcudia. A natural beach such as Es Trenc has a density of one user per 18 square metres. The beach at Benirràs in Ibiza has one user per 6.73 square metres. The minimum established by the POOT, the tourism development plan, is one user per 7.5 square metres, although some experts feel that this should be increased to one user per 15 square metres. The CITTIB regularly supplies the tourist ministry with reports on the use of land, the use of natural resources and the impact on the environment. It says that since 1956, 19.131 hectares of countryside have been developed in the Balearics. This represents 80 per cent of building in the Balearics, and five per cent of land is now built on compared to only one per cent in 1956. The government and the Council of Majorca have been trying to restrict building in rural areas.