Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 1862310 | Metric tons | NA |
| 2004 | 1983336 | Metric tons | 6.50% |
| 2005 | 2331971 | Metric tons | 17.58% |
| 2006 | 5771892 | Metric tons | 147.51% |
| 2007 | 6548796 | Metric tons | 13.46% |
| 2008 | 6500000 | Metric tons | -0.75% |
