Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 500000 | Metric tons | NA |
| 2004 | 508000 | Metric tons | 1.60% |
| 2005 | 494000 | Metric tons | -2.76% |
| 2006 | 433190 | Metric tons | -12.31% |
| 2007 | 570000 | Metric tons | 31.58% |
| 2008 | 490567 | Metric tons | -13.94% |
| 2009 | 500000 | Metric tons | 1.92% |
