Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 8.73600006103516 | Thousand metric tons | NA |
| 2003 | 6.30000019073486 | Thousand metric tons | -27.88% |
| 2004 | 9.89999961853027 | Thousand metric tons | 57.14% |
| 2005 | 9.89999961853027 | Thousand metric tons | 0.00% |
| 2006 | 9.89999961853027 | Thousand metric tons | 0.00% |
| 2007 | 9.89999961853027 | Thousand metric tons | 0.00% |
| 2008 | 22.8999996185303 | Thousand metric tons | 131.31% |
| 2009 | 30.5230007171631 | Thousand metric tons | 33.29% |
| 2010 | 44.6650009155273 | Thousand metric tons | 46.33% |
| 2011 | 78.9260025024414 | Thousand metric tons | 76.71% |
| 2012 | 78.9000015258789 | Thousand metric tons | -0.03% |
