Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 478796 | Metric tons | NA |
| 2004 | 404549 | Metric tons | -15.51 % |
| 2005 | 352374 | Metric tons | -12.90 % |
| 2006 | 363998 | Metric tons | 3.30 % |
| 2007 | 384709 | Metric tons | 5.69 % |
| 2008 | 414336 | Metric tons | 7.70 % |
| 2009 | 350000 | Metric tons | -15.53 % |
