Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 1126 | Metric tons | NA |
| 2003 | 1064 | Metric tons | -5.51% |
| 2004 | 1064 | Metric tons | 0.00% |
| 2005 | 970 | Metric tons | -8.83% |
| 2006 | 1186 | Metric tons | 22.27% |
| 2007 | 1200 | Metric tons | 1.18% |
| 2008 | 1132 | Metric tons | -5.67% |
| 2009 | 854 | Metric tons | -24.56% |
| 2010 | 952 | Metric tons | 11.48% |
| 2011 | 935 | Metric tons | -1.79% |
| 2012 | 800 | Metric tons | -14.44% |
