Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 1408 | Metric tons | NA |
| 2003 | 1310 | Metric tons | -6.96% |
| 2004 | 1337 | Metric tons | 2.06% |
| 2005 | 1123.83703613281 | Metric tons | -15.94% |
| 2006 | 995.023986816406 | Metric tons | -11.46% |
| 2007 | 860.448974609375 | Metric tons | -13.52% |
| 2008 | 709 | Metric tons | -17.60% |
| 2009 | 609 | Metric tons | -14.10% |
| 2010 | 570 | Metric tons | -6.40% |
| 2011 | 582 | Metric tons | 2.11% |
| 2012 | 663 | Metric tons | 13.92% |
