Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 51600 | Thousand metric tons | NA |
| 2003 | 48600 | Thousand metric tons | -5.81 % |
| 2004 | 54700 | Thousand metric tons | 12.55 % |
| 2005 | 54329.2421875 | Thousand metric tons | -0.68 % |
| 2006 | 52749 | Thousand metric tons | -2.91 % |
| 2007 | 52489 | Thousand metric tons | -0.49 % |
| 2008 | 53560 | Thousand metric tons | 2.04 % |
| 2009 | 26696 | Thousand metric tons | -50.16 % |
