Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 474000 | Metric tons | NA |
| 2004 | 475000 | Metric tons | 0.21 % |
| 2005 | 446000 | Metric tons | -6.11 % |
| 2006 | 470000 | Metric tons | 5.38 % |
| 2007 | 305905 | Metric tons | -34.91 % |
| 2008 | 281119 | Metric tons | -8.10 % |
| 2009 | 146318 | Metric tons | -47.95 % |
