Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 472668 | Metric tons | NA |
| 2004 | 473983 | Metric tons | 0.28% |
| 2005 | 474000 | Metric tons | 0.00% |
| 2006 | 446000 | Metric tons | -5.91% |
| 2007 | 447000 | Metric tons | 0.22% |
| 2008 | 126000 | Metric tons | -71.81% |
| 2009 | 200000 | Metric tons | 58.73% |
