Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 4500 | Kilograms | NA |
| 2003 | 4300 | Kilograms | -4.44% |
| 2004 | 5300 | Kilograms | 23.26% |
| 2005 | 5100 | Kilograms | -3.77% |
| 2006 | 5100 | Kilograms | 0.00% |
| 2007 | 5000 | Kilograms | -1.96% |
| 2008 | 4953 | Kilograms | -0.94% |
| 2009 | 5542 | Kilograms | 11.89% |
| 2010 | 6285 | Kilograms | 13.41% |
| 2011 | 5994 | Kilograms | -4.63% |
| 2012 | 6000 | Kilograms | 0.10% |
