Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 4 | Thousand metric tons | NA |
| 2003 | 5 | Thousand metric tons | 25.00% |
| 2004 | 4.5 | Thousand metric tons | -10.00% |
| 2005 | 4.5 | Thousand metric tons | 0.00% |
| 2006 | 4.5 | Thousand metric tons | 0.00% |
| 2007 | 4.5 | Thousand metric tons | 0.00% |
| 2008 | 4.5 | Thousand metric tons | 0.00% |
| 2009 | 4.5 | Thousand metric tons | 0.00% |
| 2010 | 4.40000009536743 | Thousand metric tons | -2.22% |
| 2011 | 4.5 | Thousand metric tons | 2.27% |
| 2012 | 4.5 | Thousand metric tons | 0.00% |
| 2013 | 4.5 | Thousand metric tons | 0.00% |
