Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 100 | Thousand metric tons | NA |
| 2004 | 100 | Thousand metric tons | 0.00% |
| 2005 | 100 | Thousand metric tons | 0.00% |
| 2006 | 100 | Thousand metric tons | 0.00% |
| 2007 | 100 | Thousand metric tons | 0.00% |
| 2008 | 64.5210037231445 | Thousand metric tons | -35.48% |
| 2009 | 37.9049987792969 | Thousand metric tons | -41.25% |
| 2010 | 40 | Thousand metric tons | 5.53% |
| 2011 | 1.6710000038147 | Thousand metric tons | -95.82% |
