Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 2317 | Thousand metric tons | NA |
| 2004 | 2106 | Thousand metric tons | -9.11% |
| 2005 | 1969 | Thousand metric tons | -6.51% |
| 2006 | 2124 | Thousand metric tons | 7.87% |
| 2007 | 2050 | Thousand metric tons | -3.48% |
