Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 6600 | Metric tons | NA |
| 2004 | 5500 | Metric tons | -16.67% |
| 2005 | 6700 | Metric tons | 21.82% |
| 2006 | 7500 | Metric tons | 11.94% |
| 2007 | 7136 | Metric tons | -4.85% |
| 2008 | 7000 | Metric tons | -1.91% |
| 2009 | 5000 | Metric tons | -28.57% |
