Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 77227 | Metric tons | NA |
| 2003 | 77581 | Metric tons | 0.46 % |
| 2004 | 95743 | Metric tons | 23.41 % |
| 2005 | 89541 | Metric tons | -6.48 % |
| 2006 | 78600 | Metric tons | -12.22 % |
| 2007 | 90200 | Metric tons | 14.76 % |
| 2008 | 89000 | Metric tons | -1.33 % |
