Minorca's ailing network of roads and its limited capacity to cope with the rising volume of traffic are the two biggest concerns of the Minorcan population. 31 per cent of the population polled in a survey last month said that the island's principal problems are the roads, followed by the public transport service about which 25 per cent of the population are worried about. A similar percentage of the population is also concerned about the lack of housing and 24 per cent are increasingly worried about security and 22 per cent are concerned about immigration. Housing has become a major concern because 50 per cent of residential properties are in the tourist sector. On paper there is enough residential housing for 170.186 people, but half is snapped up by the tourist industry. The poll carried out by Gadeso has also established that on each of the three islands, the people are worried about different things. In Majorca 59 per cent of the population is concerned about non-community immigration while in Ibiza the biggest worries for 37 per cent of the population are drugs and alcohol. The Gadeso report explains that the reasons behind the public's fears over non-European Union immigration in Majorca is that half of those arrested in Majorca last year were immigrants. In Palma, there have been growing worries about crime over the past few years and despite the city council's community policing campaigns, penal crime in the Balearics has risen by an alarming 50 per cent during the first four months of this year -- much higher than anywhere else in Spain. Residents and the police are also becoming increasingly worried about the runaway rate of teenage crime in Majorca. The younger generation is however more concerned about preservation of the environment. 29 per cent put the environment at the top of their list, followed by concerns over lack of housing for first time buyers and about job security.