Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 326 | Thousand metric tons | NA |
| 2003 | 287 | Thousand metric tons | -11.96% |
| 2004 | 305.071990966797 | Thousand metric tons | 6.30% |
| 2005 | 534 | Thousand metric tons | 75.04% |
| 2006 | 583 | Thousand metric tons | 9.18% |
| 2007 | 570 | Thousand metric tons | -2.23% |
| 2008 | 392 | Thousand metric tons | -31.23% |
| 2009 | 390 | Thousand metric tons | -0.51% |
