Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 43320 | Kilograms | NA |
| 2003 | 48018 | Kilograms | 10.84% |
| 2004 | 48178 | Kilograms | 0.33% |
| 2005 | 52276 | Kilograms | 8.51% |
| 2006 | 47000 | Kilograms | -10.09% |
| 2007 | 40193 | Kilograms | -14.48% |
| 2008 | 36434 | Kilograms | -9.35% |
| 2009 | 39112 | Kilograms | 7.35% |
| 2010 | 39448 | Kilograms | 0.86% |
| 2011 | 44000 | Kilograms | 11.54% |
| 2012 | 44000 | Kilograms | 0.00% |
