Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 950000 | Metric tons | NA |
| 2004 | 950000 | Metric tons | 0.00 % |
| 2005 | 1124795 | Metric tons | 18.40 % |
| 2006 | 1125000 | Metric tons | 0.02 % |
| 2007 | 950000 | Metric tons | -15.56 % |
| 2008 | 1500000 | Metric tons | 57.89 % |
| 2009 | 844804 | Metric tons | -43.68 % |
