Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 233028 | Metric tons | NA |
| 2004 | 182842 | Metric tons | -21.54% |
| 2005 | 168640 | Metric tons | -7.77% |
| 2006 | 167332 | Metric tons | -0.78% |
| 2007 | 171303 | Metric tons | 2.37% |
| 2008 | 170000 | Metric tons | -0.76% |
