Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 4400 | Metric tons | NA |
| 2004 | 4400 | Metric tons | 0.00% |
| 2005 | 4500 | Metric tons | 2.27% |
| 2006 | 4600 | Metric tons | 2.22% |
| 2007 | 4700 | Metric tons | 2.17% |
| 2008 | 4800 | Metric tons | 2.13% |
| 2009 | 11909 | Metric tons | 148.10% |
| 2010 | 17342 | Metric tons | 45.62% |
| 2011 | 12119 | Metric tons | -30.12% |
| 2012 | 11000 | Metric tons | -9.23% |
| 2013 | 11000 | Metric tons | 0.00% |
