Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 25000 | Metric tons | NA |
| 2004 | 28000 | Metric tons | 12.00 % |
| 2005 | 28000 | Metric tons | 0.00 % |
| 2006 | 28000 | Metric tons | 0.00 % |
| 2007 | 28000 | Metric tons | 0.00 % |
| 2008 | 27000 | Metric tons | -3.57 % |
| 2009 | 25000 | Metric tons | -7.41 % |
