Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 18962 | Metric tons | NA |
| 2003 | 23389 | Metric tons | 23.35 % |
| 2004 | 18767 | Metric tons | -19.76 % |
| 2005 | 15000 | Metric tons | -20.07 % |
| 2006 | 12132 | Metric tons | -19.12 % |
| 2007 | 2213 | Metric tons | -81.76 % |
| 2008 | 2000 | Metric tons | -9.62 % |
