Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 1229 | Metric tons | NA |
| 2003 | 1237 | Metric tons | 0.65% |
| 2004 | 1344 | Metric tons | 8.65% |
| 2005 | 1263 | Metric tons | -6.03% |
| 2006 | 1266 | Metric tons | 0.24% |
| 2007 | 1199 | Metric tons | -5.29% |
| 2008 | 1161 | Metric tons | -3.17% |
| 2009 | 1207 | Metric tons | 3.96% |
| 2010 | 1181 | Metric tons | -2.15% |
| 2011 | 1167 | Metric tons | -1.19% |
| 2012 | 1149 | Metric tons | -1.54% |
