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 | 60 | Thousand metric tons | -3.23% |
| 2004 | 60 | Thousand metric tons | 0.00% |
| 2005 | 60 | Thousand metric tons | 0.00% |
| 2006 | 60 | Thousand metric tons | 0.00% |
| 2007 | 60 | Thousand metric tons | 0.00% |
| 2008 | 62 | Thousand metric tons | 3.33% |
| 2009 | 62 | Thousand metric tons | 0.00% |
| 2010 | 89 | Thousand metric tons | 43.55% |
| 2011 | 62 | Thousand metric tons | -30.34% |
| 2012 | 60 | Thousand metric tons | -3.23% |
