Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 2351122 | Metric tons, gross weight | NA |
| 2003 | 2813000 | Metric tons, gross weight | 19.65% |
| 2004 | 2965000 | Metric tons, gross weight | 5.40% |
| 2005 | 2812000 | Metric tons, gross weight | -5.16% |
| 2006 | 3030000 | Metric tons, gross weight | 7.75% |
