Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 250 | Thousand metric tons | NA |
| 2003 | 250 | Thousand metric tons | 0.00% |
| 2004 | 250 | Thousand metric tons | 0.00% |
| 2005 | 250 | Thousand metric tons | 0.00% |
| 2006 | 1488.88305664063 | Thousand metric tons | 495.55% |
| 2007 | 1550 | Thousand metric tons | 4.10% |
| 2008 | 1347 | Thousand metric tons | -13.10% |
| 2009 | 1315 | Thousand metric tons | -2.38% |
| 2010 | 1305 | Thousand metric tons | -0.76% |
| 2011 | 1460 | Thousand metric tons | 11.88% |
| 2012 | 1390 | Thousand metric tons | -4.79% |
