It is an observer member of the Collective Security Treaty Organisation (CSTO) The country also signed the Stability Pact for South Eastern Europe. The Serbian Armed Forces take part in several multinational peacekeeping missions, including deployments in Lebanon, Cyprus, Ivory Coast, and Liberia. Serbia is a major producer and exporter of military equipment in the region. Defence exports totaled around $600 million in 2018. The defence industry has seen significant growth over the years and it continues to grow on a yearly basis. Serbia is one of the countries with the largest number of firearms in the civilian population in the world. Administrative divisions Serbia is a unitary state composed of municipalities/cities, districts, and two autonomous provinces. In Serbia, excluding Kosovo, there are 145 municipalities (opštine) and 29 cities (gradovi), which form the basic units of local self-government. Apart from municipalities/cities, there are 24 districts (okruzi, 10 most populated listed below), with the City of Belgrade constituting an additional district. Except for Belgrade, which has an elected local government, districts are regional centres of state authority, but have no powers of their own; they present purely administrative divisions. The Constitution of Serbia recognizes two autonomous provinces, Vojvodina in the north, and the disputed territory of Kosovo and Metohija in the south, while the remaining area of Central Serbia never had its own regional authority. Following the Kosovo War, UN peacekeepers entered Kosovo and Metohija, as per UNSC Resolution 1244. The government of Serbia does not recognise Kosovo's February 2008 declaration of independence, considering it illegal and illegitimate. Demographics census, Serbia (excluding Kosovo) has a total population of 7,186,862 and the overall population density is medium as it stands at 92.8 inhabitants per square kilometre. The census was not conducted in Kosovo which held its own census that numbered their total population at 1,739,825, excluding Serb-inhabited North Kosovo, as Serbs from that area (about 50,000) boycotted the census. Serbia has been enduring a demographic crisis since the beginning of the 1990s, with a death rate that has continuously exceeded its birth rate. It is estimated that 300,000 people left Serbia during the 1990s, 20% of whom had a higher education. Serbia subsequently has one of the oldest populations in the world, with the average age of 43.3 years, and its population is shrinking at one of the fastest rates in the world. A fifth of all households consist of only one