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 % |
