Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 6110 | Thousand metric tons | NA |
| 2004 | 6990 | Thousand metric tons | 14.40% |
| 2005 | 8610 | Thousand metric tons | 23.18% |
| 2006 | 13700 | Thousand metric tons | 59.12% |
| 2007 | 19500 | Thousand metric tons | 42.34% |
