Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 151904 | Kilograms | NA |
| 2003 | 140861 | Kilograms | -7.27% |
| 2004 | 129478 | Kilograms | -8.08% |
| 2005 | 119549 | Kilograms | -7.67% |
| 2006 | 103513 | Kilograms | -13.41% |
| 2007 | 102211 | Kilograms | -1.26% |
| 2008 | 94909 | Kilograms | -7.14% |
| 2009 | 96573 | Kilograms | 1.75% |
| 2010 | 102147 | Kilograms | 5.77% |
| 2011 | 101975 | Kilograms | -0.17% |
| 2012 | 103713 | Kilograms | 1.70% |
