Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 1224 | Thousand metric tons | NA |
| 2003 | 1268 | Thousand metric tons | 3.59 % |
| 2004 | 1392 | Thousand metric tons | 9.78 % |
| 2005 | 1384 | Thousand metric tons | -0.57 % |
| 2006 | 1800 | Thousand metric tons | 30.06 % |
| 2007 | 1800 | Thousand metric tons | 0.00 % |
| 2008 | 1800 | Thousand metric tons | 0.00 % |
