Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 78000 | Metric tons | NA |
| 2004 | 63000 | Metric tons | -19.23% |
| 2005 | 63000 | Metric tons | 0.00% |
| 2006 | 63000 | Metric tons | 0.00% |
| 2007 | 63000 | Metric tons | 0.00% |
| 2008 | 63000 | Metric tons | 0.00% |
| 2009 | 63000 | Metric tons | 0.00% |
| 2010 | 60000 | Metric tons | -4.76% |
| 2011 | 63000 | Metric tons | 5.00% |
| 2012 | 63000 | Metric tons | 0.00% |
