Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 502800 | Metric tons | NA |
| 2003 | 495000 | Metric tons | -1.55 % |
| 2004 | 531000 | Metric tons | 7.27 % |
| 2005 | 512000 | Metric tons | -3.58 % |
| 2006 | 497000 | Metric tons | -2.93 % |
| 2007 | 452000 | Metric tons | -9.05 % |
| 2008 | 429000 | Metric tons | -5.09 % |
