Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 65 | Thousand metric tons | NA |
| 2003 | 65 | Thousand metric tons | 0.00 % |
| 2004 | 65 | Thousand metric tons | 0.00 % |
| 2005 | 65 | Thousand metric tons | 0.00 % |
| 2006 | 65 | Thousand metric tons | 0.00 % |
| 2007 | 65 | Thousand metric tons | 0.00 % |
| 2008 | 65 | Thousand metric tons | 0.00 % |
| 2009 | 49 | Thousand metric tons | -24.62 % |
| 2010 | 45 | Thousand metric tons | -8.16 % |
| 2011 | 74 | Thousand metric tons | 64.44 % |
| 2012 | 114 | Thousand metric tons | 54.05 % |
