Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 57738 | Metric tons | NA |
| 2004 | 53721 | Metric tons | -6.96% |
| 2005 | 57534 | Metric tons | 7.10% |
| 2006 | 75400 | Metric tons | 31.05% |
| 2007 | 90232 | Metric tons | 19.67% |
| 2008 | 105815 | Metric tons | 17.27% |
