Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 5618 | Kilograms | NA |
| 2003 | 5500 | Kilograms | -2.10% |
| 2004 | 5300 | Kilograms | -3.64% |
| 2005 | 5400 | Kilograms | 1.89% |
| 2006 | 5400 | Kilograms | 0.00% |
| 2007 | 5500 | Kilograms | 1.85% |
| 2008 | 5500 | Kilograms | 0.00% |
| 2009 | 5600 | Kilograms | 1.82% |
