Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2005 | 1.31099998950958 | Thousand metric tons | NA |
| 2006 | 1.47800004482269 | Thousand metric tons | 12.74% |
| 2007 | 1.5 | Thousand metric tons | 1.49% |
| 2008 | 1.39999997615814 | Thousand metric tons | -6.67% |
