Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 561 | Thousand metric tons | NA |
| 2004 | 610 | Thousand metric tons | 8.73% |
| 2005 | 572 | Thousand metric tons | -6.23% |
| 2006 | 607 | Thousand metric tons | 6.12% |
| 2007 | 620 | Thousand metric tons | 2.14% |
