Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 318 | Metric tons, gross weight | NA |
| 2003 | 341 | Metric tons, gross weight | 7.23 % |
| 2004 | 360 | Metric tons, gross weight | 5.57 % |
| 2005 | 410 | Metric tons, gross weight | 13.89 % |
