Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 60 | Thousand metric tons | NA |
| 2003 | 70 | Thousand metric tons | 16.67% |
| 2004 | 70 | Thousand metric tons | 0.00% |
| 2005 | 60 | Thousand metric tons | -14.29% |
| 2006 | 50 | Thousand metric tons | -16.67% |
| 2007 | 50 | Thousand metric tons | 0.00% |
| 2008 | 37 | Thousand metric tons | -26.00% |
| 2009 | 32 | Thousand metric tons | -13.51% |
| 2010 | 36 | Thousand metric tons | 12.50% |
| 2011 | 38 | Thousand metric tons | 5.56% |
| 2012 | 37 | Thousand metric tons | -2.63% |
