Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 669 | Thousand metric tons | NA |
| 2004 | 725 | Thousand metric tons | 8.37% |
| 2005 | 790 | Thousand metric tons | 8.97% |
| 2006 | 896 | Thousand metric tons | 13.42% |
| 2007 | 750 | Thousand metric tons | -16.29% |
