Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 25741 | Metric tons | NA |
| 2004 | 22337 | Metric tons | -13.22% |
| 2005 | 20266 | Metric tons | -9.27% |
| 2006 | 11063 | Metric tons | -45.41% |
| 2007 | 6879 | Metric tons | -37.82% |
