Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 2042 | Thousand metric tons | NA |
| 2004 | 2412 | Thousand metric tons | 18.12% |
| 2005 | 3675 | Thousand metric tons | 52.36% |
| 2006 | 3800 | Thousand metric tons | 3.40% |
| 2007 | 3900 | Thousand metric tons | 2.63% |
