Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 14800 | Kilograms | NA |
| 2003 | 14000 | Kilograms | -5.41% |
| 2004 | 13700 | Kilograms | -2.14% |
| 2005 | 13300 | Kilograms | -2.92% |
| 2006 | 14400 | Kilograms | 8.27% |
| 2007 | 12800 | Kilograms | -11.11% |
| 2008 | 11900 | Kilograms | -7.03% |
| 2009 | 12700 | Kilograms | 6.72% |
