Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 31779 | Thousand metric tons | NA |
| 2004 | 32600 | Thousand metric tons | 2.58% |
| 2005 | 45800 | Thousand metric tons | 40.49% |
| 2006 | 49500 | Thousand metric tons | 8.08% |
| 2007 | 53100 | Thousand metric tons | 7.27% |
