Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 2642 | Thousand metric tons | NA |
| 2003 | 2476 | Thousand metric tons | -6.28 % |
| 2004 | 2588 | Thousand metric tons | 4.52 % |
| 2005 | 2709 | Thousand metric tons | 4.68 % |
| 2006 | 2952 | Thousand metric tons | 8.97 % |
| 2007 | 2950 | Thousand metric tons | -0.07 % |
| 2008 | 2900 | Thousand metric tons | -1.69 % |
