Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 3503589 | Metric tons | NA |
| 2004 | 3751874 | Metric tons | 7.09% |
| 2005 | 3767662 | Metric tons | 0.42% |
| 2006 | 3815173 | Metric tons | 1.26% |
| 2007 | 3800000 | Metric tons | -0.40% |
