Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 12063 | Metric tons | NA |
| 2003 | 12217 | Metric tons | 1.28 % |
| 2004 | 12202 | Metric tons | -0.12 % |
| 2005 | 11739 | Metric tons | -3.79 % |
| 2006 | 9528 | Metric tons | -18.83 % |
| 2007 | 11835 | Metric tons | 24.21 % |
| 2008 | 13000 | Metric tons | 9.84 % |
| 2009 | 13000 | Metric tons | 0.00 % |
