Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 54 | Thousand metric tons | NA |
| 2003 | 54 | Thousand metric tons | 0.00% |
| 2004 | 54 | Thousand metric tons | 0.00% |
| 2005 | 54 | Thousand metric tons | 0.00% |
| 2006 | 54 | Thousand metric tons | 0.00% |
| 2007 | 54 | Thousand metric tons | 0.00% |
| 2008 | 56 | Thousand metric tons | 3.70% |
| 2009 | 42 | Thousand metric tons | -25.00% |
| 2010 | 32 | Thousand metric tons | -23.81% |
| 2011 | 73 | Thousand metric tons | 128.13% |
| 2012 | 73 | Thousand metric tons | 0.00% |
