Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 1051 | Thousand metric tons | NA |
| 2004 | 1014 | Thousand metric tons | -3.52% |
| 2005 | 1007 | Thousand metric tons | -0.69% |
| 2006 | 1158 | Thousand metric tons | 15.00% |
| 2007 | 1278 | Thousand metric tons | 10.36% |
