Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 1350 | Metric tons | NA |
| 2003 | 1240 | Metric tons | -8.15% |
| 2004 | 1250 | Metric tons | 0.81% |
| 2005 | 1230 | Metric tons | -1.60% |
| 2006 | 1160 | Metric tons | -5.69% |
| 2007 | 1280 | Metric tons | 10.34% |
| 2008 | 1250 | Metric tons | -2.34% |
| 2009 | 1250 | Metric tons | 0.00% |
| 2010 | 1280 | Metric tons | 2.40% |
| 2011 | 1120 | Metric tons | -12.50% |
| 2012 | 1060 | Metric tons | -5.36% |
