Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 90000 | Kilograms | NA |
| 2003 | 90000 | Kilograms | 0.00% |
| 2004 | 93000 | Kilograms | 3.33% |
| 2005 | 90000 | Kilograms | -3.23% |
| 2006 | 85000 | Kilograms | -5.56% |
| 2007 | 85000 | Kilograms | 0.00% |
| 2008 | 85000 | Kilograms | 0.00% |
| 2009 | 90000 | Kilograms | 5.88% |
| 2010 | 90000 | Kilograms | 0.00% |
| 2011 | 91000 | Kilograms | 1.11% |
| 2012 | 93000 | Kilograms | 2.20% |
