Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 10000 | Metric tons | NA |
| 2003 | 12000 | Metric tons | 20.00% |
| 2004 | 12000 | Metric tons | 0.00% |
| 2005 | 10000 | Metric tons | -16.67% |
| 2006 | 9000 | Metric tons | -10.00% |
| 2007 | 11000 | Metric tons | 22.22% |
| 2008 | 11000 | Metric tons | 0.00% |
| 2009 | 9800 | Metric tons | -10.91% |
| 2010 | 6700 | Metric tons | -31.63% |
| 2011 | 6300 | Metric tons | -5.97% |
| 2012 | 6300 | Metric tons | 0.00% |
