Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 266100 | Kilograms | NA |
| 2003 | 282000 | Kilograms | 5.98 % |
| 2004 | 259000 | Kilograms | -8.16 % |
| 2005 | 262000 | Kilograms | 1.16 % |
| 2006 | 247000 | Kilograms | -5.73 % |
| 2007 | 247000 | Kilograms | 0.00 % |
| 2008 | 215000 | Kilograms | -12.96 % |
| 2009 | 222000 | Kilograms | 3.26 % |
