Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 294 | Metric tons | NA |
| 2003 | 307 | Metric tons | 4.42 % |
| 2004 | 293 | Metric tons | -4.56 % |
| 2005 | 309.899993896484 | Metric tons | 5.77 % |
| 2006 | 268.200012207031 | Metric tons | -13.46 % |
| 2007 | 270 | Metric tons | 0.67 % |
| 2008 | 265 | Metric tons | -1.85 % |
| 2009 | 265 | Metric tons | 0.00 % |
