Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 1330 | Thousand metric tons | NA |
| 2004 | 890 | Thousand metric tons | -33.08 % |
| 2005 | 930 | Thousand metric tons | 4.49 % |
| 2006 | 1370 | Thousand metric tons | 47.31 % |
| 2007 | 1280 | Thousand metric tons | -6.57 % |
| 2008 | 1280 | Thousand metric tons | 0.00 % |
| 2009 | 1280 | Thousand metric tons | 0.00 % |
