FACTBOX: Key facts on Slovenia

(Reuters) - Slovenia's ruling SDS is leading the center-left opposition in most opinion polls ahead of Sunday's parliamentary election, its fifth since independence from former Yugoslavia in 1991.

Here are some key facts on Slovenia.

POPULATION: 2 million; 90 percent are Slovenes who speak Slovenian, a south Slav language written in Latin script, and most of them are Roman Catholics. The remainder includes Serb, Croat, Hungarian, Italian and Bosnian minorities.

POLITICAL STRUCTURE: Parliamentary democracy. A centre-right coalition ended 12 years of mostly centre-left rule in a 2004 election. Parliament, elected for a period of four years, has 90 seats, with two seats reserved for Italian and Hungarian minority deputies. The threshold for a seat in parliament is 4 percent of the vote. There are nine parties in the current parliament.

ELECTORATE: Some 1.7 million eligible voters will choose from some 1,400 candidates. Polling stations open at 1 a.m. EDT and close at 1 p.m. EDT. Preliminary official results are expected around 5 p.m. EDT.

ECONOMY: Slovenia adopted the euro in January 2007, as the first of 10 new states that joined the EU three years earlier. Its booming economy expanded a record 6.8 percent in 2007. Inflation is a big worry. It has accelerated since Slovenia joined the euro zone to reach 6 percent year-on-year in August from 3.4 percent a year ago.

EXPORTS: Main exports are cars, Gorenje household appliances and generic drugs made by Krka and Lek. The sole car maker, Revoz, is a subsidiary of France's Renault.

MODERN HISTORY: Slovenia was part of Austro-Hungarian empire until its demise in 1918 when Slovenia joined the Kingdom of Serbs, Croats and Slovenes, later renamed Yugoslavia. In 1945, the kingdom was replaced by the communist Yugoslav federation.

Slovenia was the first of Yugoslavia's six republics to hold free elections in 1990. It declared independence in June 1991, prompting a 10-day war with the Yugoslav army, but won international recognition in 1992 and joined the European Union and NATO in 2004.

SIZE: At 20,250 sq km (7,800 sq miles), it is around the size of Canada's Lake Ontario. More than half the country consists of mountainous forests.

(Reporting by Marja Novak in Ljubljana)