Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 688086 | Metric tons | NA |
| 2003 | 691380 | Metric tons | 0.48 % |
| 2004 | 868574 | Metric tons | 25.63 % |
| 2005 | 844369 | Metric tons | -2.79 % |
| 2006 | 874601 | Metric tons | 3.58 % |
| 2007 | 1018156 | Metric tons | 16.41 % |
| 2008 | 1107789 | Metric tons | 8.80 % |
