Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 61379 | Kilograms | NA |
| 2003 | 67832 | Kilograms | 10.51% |
| 2004 | 73670 | Kilograms | 8.61% |
| 2005 | 68483 | Kilograms | -7.04% |
| 2006 | 58349 | Kilograms | -14.80% |
| 2007 | 65000 | Kilograms | 11.40% |
| 2008 | 67463 | Kilograms | 3.79% |
| 2009 | 63600 | Kilograms | -5.73% |
| 2010 | 62900 | Kilograms | -1.10% |
| 2011 | 61760 | Kilograms | -1.81% |
| 2012 | 53100 | Kilograms | -14.02% |
