Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 3462 | Thousand metric tons | NA |
| 2003 | 3622 | Thousand metric tons | 4.62 % |
| 2004 | 3797.60302734375 | Thousand metric tons | 4.85 % |
| 2005 | 3999.1220703125 | Thousand metric tons | 5.31 % |
| 2006 | 4111.533203125 | Thousand metric tons | 2.81 % |
| 2007 | 4439.966796875 | Thousand metric tons | 7.99 % |
| 2008 | 4622.3291015625 | Thousand metric tons | 4.11 % |
