Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 2497 | Metric tons | NA |
| 2004 | 2233 | Metric tons | -10.57 % |
| 2005 | 2297 | Metric tons | 2.87 % |
| 2006 | 2287 | Metric tons | -0.44 % |
| 2007 | 1933 | Metric tons | -15.48 % |
| 2008 | 2116 | Metric tons | 9.47 % |
| 2009 | 2200 | Metric tons | 3.97 % |
