Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 370455 | Metric tons | NA |
| 2004 | 536008 | Metric tons | 44.69 % |
| 2005 | 580000 | Metric tons | 8.21 % |
| 2006 | 650000 | Metric tons | 12.07 % |
| 2007 | 580000 | Metric tons | -10.77 % |
