Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 27198 | Metric tons | NA |
| 2004 | 25263 | Metric tons | -7.11% |
| 2005 | 25657 | Metric tons | 1.56% |
| 2006 | 25120 | Metric tons | -2.09% |
| 2007 | 26739 | Metric tons | 6.45% |
| 2008 | 17682 | Metric tons | -33.87% |
| 2009 | 18134 | Metric tons | 2.56% |
