Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 2396 | Thousand metric tons | NA |
| 2003 | 2075 | Thousand metric tons | -13.40% |
| 2004 | 2240 | Thousand metric tons | 7.95% |
| 2005 | 2276 | Thousand metric tons | 1.61% |
| 2006 | 2565 | Thousand metric tons | 12.70% |
