Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 32506 | Kilograms | NA |
| 2003 | 29749 | Kilograms | -8.48% |
| 2004 | 28466 | Kilograms | -4.31% |
| 2005 | 27904 | Kilograms | -1.97% |
| 2006 | 44131 | Kilograms | 58.15% |
| 2007 | 42021 | Kilograms | -4.78% |
| 2008 | 42046 | Kilograms | 0.06% |
| 2009 | 46588 | Kilograms | 10.80% |
| 2010 | 63138 | Kilograms | 35.52% |
| 2011 | 59140 | Kilograms | -6.33% |
| 2012 | 56100 | Kilograms | -5.14% |
