Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 5 | Thousand metric tons | NA |
| 2004 | 6 | Thousand metric tons | 20.00% |
| 2005 | 6 | Thousand metric tons | 0.00% |
| 2006 | 6.5 | Thousand metric tons | 8.33% |
| 2007 | 7 | Thousand metric tons | 7.69% |
| 2008 | 7 | Thousand metric tons | 0.00% |
| 2009 | 7 | Thousand metric tons | 0.00% |
