Western Sahara is a non-self governing territory; approximately 75% is under Moroccan control. It was inhabited almost entirely by Sahrawi pastoral nomads until the mid-20th century. Their traditional vast migratory ranges, based on following unpredictable rainfall, did not coincide with colonial and later international borders. Since the 1930s, most Sahrawis have been compelled to adopt a sedentary lifestyle and to live in urban settings as a result of fighting, the presence of minefields, job opportunities in the phosphate industry, prolonged drought, the closure of Western Sahara's border with Mauritania from 1979-2002, and the construction of the defensive berm separating Moroccan- and Polisario-controlled (Sahrawi liberalization movement) areas. Morocco supported rapid urbanization to facilitate surveillance and security. ++ Today more than 80% of Western Sahara's population lives in urban areas; more than 40% live in the administrative center Laayoune. Moroccan immigration has altered the composition and dramatically increased the size of Western Sahara's population. Morocco maintains a large military presence in Western Sahara and has encouraged its citizens to settle there, offering bonuses, pay raises, and food subsidies to civil servants and a tax exemption, in order to integrate Western Sahara into the Moroccan Kingdom and, Sahrawis contend, to marginalize the native population. ++ Western Saharan Sahrawis have been migrating to Europe, principally to former colonial ruler Spain, since the 1950s. Many who moved to refugee camps in Tindouf, Algeria, also have migrated to Spain and Italy, usually alternating between living in cities abroad with periods back at the camps. The Polisario claims that the population of the Tindouf camps is about 155,000, but this figure may include thousands of Arabs and Tuaregs from neighboring countries. Because international organizations have been unable to conduct an independent census in Tindouf, the UNHCR bases its aid on a figure of 90,000 refugees. Western Saharan coastal towns emerged as key migration transit points (for reaching Spain's Canary Islands) in the mid-1990s, when Spain's and Italy's tightening of visa restrictions and EU pressure on Morocco and other North African countries to control illegal migration pushed Sub-Saharan African migrants to shift their routes to the south.