Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 222340 | Thousand metric tons | NA |
| 2004 | 272450 | Thousand metric tons | 22.54% |
| 2005 | 353240 | Thousand metric tons | 29.65% |
| 2006 | 419150 | Thousand metric tons | 18.66% |
| 2007 | 489240 | Thousand metric tons | 16.72% |
