Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 1228388 | Metric tons | NA |
| 2004 | 1536448 | Metric tons | 25.08% |
| 2005 | 1500000 | Metric tons | -2.37% |
| 2006 | 1400000 | Metric tons | -6.67% |
| 2007 | 1500000 | Metric tons | 7.14% |
| 2008 | 1500000 | Metric tons | 0.00% |
| 2009 | 1500000 | Metric tons | 0.00% |
