Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 1178 | Thousand metric tons | NA |
| 2003 | 1370 | Thousand metric tons | 16.30 % |
| 2004 | 1186 | Thousand metric tons | -13.43 % |
| 2005 | 1114 | Thousand metric tons | -6.07 % |
| 2006 | 1269 | Thousand metric tons | 13.91 % |
| 2007 | 1300 | Thousand metric tons | 2.44 % |
| 2008 | 1300 | Thousand metric tons | 0.00 % |
