Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 4215 | Metric tons | NA |
| 2003 | 3359 | Metric tons | -20.31% |
| 2004 | 2745 | Metric tons | -18.28% |
| 2005 | 2857 | Metric tons | 4.08% |
| 2006 | 2398 | Metric tons | -16.07% |
| 2007 | 2263 | Metric tons | -5.63% |
| 2008 | 2605 | Metric tons | 15.11% |
| 2009 | 2412 | Metric tons | -7.41% |
| 2010 | 2668 | Metric tons | 10.61% |
| 2011 | 3346 | Metric tons | 25.41% |
| 2012 | 3726 | Metric tons | 11.36% |
| 2013 | 3700 | Metric tons | -0.70% |
