Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 6690 | Metric tons | NA |
| 2004 | 4838 | Metric tons | -27.68% |
| 2005 | 5820 | Metric tons | 20.30% |
| 2006 | 5847 | Metric tons | 0.46% |
| 2007 | 6704 | Metric tons | 14.66% |
| 2008 | 6500 | Metric tons | -3.04% |
