Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 2710 | Metric tons | NA |
| 2004 | 2800 | Metric tons | 3.32 % |
| 2005 | 4080 | Metric tons | 45.71 % |
| 2006 | 3790 | Metric tons | -7.11 % |
| 2007 | 4210 | Metric tons | 11.08 % |
| 2008 | 4300 | Metric tons | 2.14 % |
| 2009 | 4300 | Metric tons | 0.00 % |
