Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 1846 | Thousand metric tons | NA |
| 2004 | 1506 | Thousand metric tons | -18.42% |
| 2005 | 1694 | Thousand metric tons | 12.48% |
| 2006 | 1479 | Thousand metric tons | -12.69% |
| 2007 | 2243 | Thousand metric tons | 51.66% |
| 2008 | 2092 | Thousand metric tons | -6.73% |
| 2009 | 1760 | Thousand metric tons | -15.87% |
