Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 56043 | Kilograms | NA |
| 2003 | 50535 | Kilograms | -9.83% |
| 2004 | 42911 | Kilograms | -15.09% |
| 2005 | 44230 | Kilograms | 3.07% |
| 2006 | 51957 | Kilograms | 17.47% |
| 2007 | 48850 | Kilograms | -5.98% |
| 2008 | 41160 | Kilograms | -15.74% |
| 2009 | 42364 | Kilograms | 2.93% |
| 2010 | 36360 | Kilograms | -14.17% |
| 2011 | 35728 | Kilograms | -1.74% |
| 2012 | 40000 | Kilograms | 11.96% |
