Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 8615 | Kilograms | NA |
| 2003 | 8143 | Kilograms | -5.48% |
| 2004 | 8021 | Kilograms | -1.50% |
| 2005 | 8318 | Kilograms | 3.70% |
| 2006 | 8904 | Kilograms | 7.04% |
| 2007 | 8869 | Kilograms | -0.39% |
| 2008 | 6868 | Kilograms | -22.56% |
| 2009 | 7708 | Kilograms | 12.23% |
| 2010 | 8544 | Kilograms | 10.85% |
| 2011 | 8691 | Kilograms | 1.72% |
| 2012 | 7233 | Kilograms | -16.78% |
