Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 44809 | Thousand metric tons | NA |
| 2004 | 46374 | Thousand metric tons | 3.49% |
| 2005 | 44524 | Thousand metric tons | -3.99% |
| 2006 | 47224 | Thousand metric tons | 6.06% |
| 2007 | 48550 | Thousand metric tons | 2.81% |
