Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 60 | Thousand metric tons | NA |
| 2004 | 5.72499990463257 | Thousand metric tons | -90.46% |
| 2005 | 5.69999980926514 | Thousand metric tons | -0.44% |
| 2006 | 5.5 | Thousand metric tons | -3.51% |
| 2007 | 5.5 | Thousand metric tons | 0.00% |
| 2008 | 5.5 | Thousand metric tons | 0.00% |
