Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 152917 | Metric tons | NA |
| 2004 | 129502 | Metric tons | -15.31% |
| 2005 | 107265 | Metric tons | -17.17% |
| 2006 | 102400 | Metric tons | -4.54% |
| 2007 | 102000 | Metric tons | -0.39% |
