Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 2418 | Thousand metric tons | NA |
| 2004 | 2444 | Thousand metric tons | 1.08% |
| 2005 | 2495 | Thousand metric tons | 2.09% |
| 2006 | 2163 | Thousand metric tons | -13.31% |
| 2007 | 2125.89990234375 | Thousand metric tons | -1.72% |
| 2008 | 2176.30004882813 | Thousand metric tons | 2.37% |
| 2009 | 2100 | Thousand metric tons | -3.51% |
