Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 1386 | Thousand metric tons | NA |
| 2004 | 1158 | Thousand metric tons | -16.45% |
| 2005 | 1081 | Thousand metric tons | -6.65% |
| 2006 | 1147 | Thousand metric tons | 6.11% |
| 2007 | 1069 | Thousand metric tons | -6.80% |
| 2008 | 441 | Thousand metric tons | -58.75% |
