Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 86100 | Metric tons | NA |
| 2004 | 65900 | Metric tons | -23.46% |
| 2005 | 54800 | Metric tons | -16.84% |
| 2006 | 73300 | Metric tons | 33.76% |
| 2007 | 80700 | Metric tons | 10.10% |
| 2008 | 83900 | Metric tons | 3.97% |
| 2009 | 80000 | Metric tons | -4.65% |
