Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 62 | Thousand metric tons | NA |
| 2003 | 62 | Thousand metric tons | 0.00% |
| 2004 | 62 | Thousand metric tons | 0.00% |
| 2005 | 55 | Thousand metric tons | -11.29% |
| 2006 | 30 | Thousand metric tons | -45.45% |
| 2007 | 26 | Thousand metric tons | -13.33% |
| 2008 | 26 | Thousand metric tons | 0.00% |
| 2009 | 19.7660007476807 | Thousand metric tons | -23.98% |
| 2010 | 20 | Thousand metric tons | 1.18% |
| 2011 | 3 | Thousand metric tons | -85.00% |
