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.[12] The country has the fourth-highest per capita income in the world on the World Bank and IMF lists, as well as ninth-highest on a more comprehensive [13] CIA list. On a per-capita basis, it is the world's largest producer of oil and natural gas outside the Middle East.[14][15] From 2001 to 2006,[16] and then again from 2009 to 2014, Norway had the highest Human Development Index ranking in the world.[8][17][18][19] Norway has also topped the Legatum Prosperity Index for the last five years