Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 192000 | Kilograms | NA |
| 2003 | 205000 | Kilograms | 6.77% |
| 2004 | 215000 | Kilograms | 4.88% |
| 2005 | 225000 | Kilograms | 4.65% |
| 2006 | 245000 | Kilograms | 8.89% |
| 2007 | 275000 | Kilograms | 12.24% |
| 2008 | 285000 | Kilograms | 3.64% |
| 2009 | 320000 | Kilograms | 12.28% |
| 2010 | 345000 | Kilograms | 7.81% |
| 2011 | 362000 | Kilograms | 4.93% |
| 2012 | 403000 | Kilograms | 11.33% |
