Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 5158 | Kilograms | NA |
| 2003 | 5362 | Kilograms | 3.96% |
| 2004 | 5248 | Kilograms | -2.13% |
| 2005 | 3971 | Kilograms | -24.33% |
| 2006 | 3421 | Kilograms | -13.85% |
| 2007 | 3500 | Kilograms | 2.31% |
| 2008 | 3400 | Kilograms | -2.86% |
| 2009 | 3450 | Kilograms | 1.47% |
| 2010 | 3500 | Kilograms | 1.45% |
| 2011 | 3550 | Kilograms | 1.43% |
| 2012 | 3600 | Kilograms | 1.41% |
