Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 7000 | Thousand metric tons | NA |
| 2003 | 7700 | Thousand metric tons | 10.00 % |
| 2004 | 5000 | Thousand metric tons | -35.06 % |
| 2005 | 5800 | Thousand metric tons | 16.00 % |
| 2006 | 7200 | Thousand metric tons | 24.14 % |
| 2007 | 9000 | Thousand metric tons | 25.00 % |
| 2008 | 9000 | Thousand metric tons | 0.00 % |
