Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2006 | 1071.14001464844 | Thousand metric tons | NA |
| 2007 | 1169.0400390625 | Thousand metric tons | 9.14% |
| 2008 | 954.369995117188 | Thousand metric tons | -18.36% |
| 2009 | 757 | Thousand metric tons | -20.68% |
