Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 363 | Thousand metric tons | NA |
| 2004 | 340 | Thousand metric tons | -6.34% |
| 2005 | 330 | Thousand metric tons | -2.94% |
| 2006 | 340 | Thousand metric tons | 3.03% |
| 2007 | 330 | Thousand metric tons | -2.94% |
