Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 157530 | Kilograms | NA |
| 2003 | 172619 | Kilograms | 9.58% |
| 2004 | 173224 | Kilograms | 0.35% |
| 2005 | 208002 | Kilograms | 20.08% |
| 2006 | 202826 | Kilograms | -2.49% |
| 2007 | 170236 | Kilograms | -16.07% |
| 2008 | 179870 | Kilograms | 5.66% |
| 2009 | 183995 | Kilograms | 2.29% |
| 2010 | 164084 | Kilograms | -10.82% |
| 2011 | 166187 | Kilograms | 1.28% |
| 2012 | 161325 | Kilograms | -2.93% |
