Norway is a sovereign and unitary monarchy whose territory comprises the western portion of the Scandinavian Peninsula plus the island Jan Mayen and the archipelago of Svalbard. The country maintains a combination of market economy and a Nordic welfare model with universal health care and a comprehensive social security system. Norway has extensive reserves of petroleum, natural gas, minerals, lumber, seafood, fresh water and hydropower. The petroleum industry accounts for around a quarter of the country's gross domestic product (GDP). On a per-capita basis, Norway is the world's largest producer of oil and natural gas outside the Middle East.