Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 168411 | Kilograms | NA |
| 2003 | 170068 | Kilograms | 0.98% |
| 2004 | 163148 | Kilograms | -4.07% |
| 2005 | 164186 | Kilograms | 0.64% |
| 2006 | 159340 | Kilograms | -2.95% |
| 2007 | 156975 | Kilograms | -1.48% |
| 2008 | 172031 | Kilograms | 9.59% |
| 2009 | 192832 | Kilograms | 12.09% |
| 2010 | 189000 | Kilograms | -1.99% |
| 2011 | 199642 | Kilograms | 5.63% |
| 2012 | 217800 | Kilograms | 9.10% |
