Coal mining produced 4.9 millions tonnes of coal in 2012, of which over 2 million tonnes were exported.[5] New Zealand coal reserves are in excess of 15 billion tonnes, mainly in Waikato, Taranaki, West Coast, Otago and Southland.[4] Over 80% of the reserves are in Southland lignite deposits worth $100 billion.[2] Coal is produced from four underground and 21 opencast mines.[6] The largest coal mining company is Solid Energy, a state-owned enterprise.