Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 35850 | Kilograms | NA |
| 2003 | 37844 | Kilograms | 5.56 % |
| 2004 | 35464 | Kilograms | -6.29 % |
| 2005 | 37490 | Kilograms | 5.71 % |
| 2006 | 36141 | Kilograms | -3.60 % |
| 2007 | 38792 | Kilograms | 7.34 % |
| 2008 | 35726 | Kilograms | -7.90 % |
| 2009 | 37047 | Kilograms | 3.70 % |
