Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 1770 | Metric tons | NA |
| 2003 | 1894 | Metric tons | 7.01% |
| 2004 | 2158 | Metric tons | 13.94% |
| 2005 | 4101 | Metric tons | 90.04% |
| 2006 | 6233 | Metric tons | 51.99% |
| 2007 | 10171 | Metric tons | 63.18% |
| 2008 | 8790 | Metric tons | -13.58% |
| 2009 | 8668 | Metric tons | -1.39% |
| 2010 | 9638 | Metric tons | 11.19% |
| 2011 | 10226 | Metric tons | 6.10% |
| 2012 | 10000 | Metric tons | -2.21% |
| 2013 | 10000 | Metric tons | 0.00% |
