Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 260574 | Metric tons | NA |
| 2003 | 279254 | Metric tons | 7.17 % |
| 2004 | 327432 | Metric tons | 17.25 % |
| 2005 | 336376 | Metric tons | 2.73 % |
| 2006 | 241536 | Metric tons | -28.19 % |
| 2007 | 230500 | Metric tons | -4.57 % |
| 2008 | 172093 | Metric tons | -25.34 % |
