Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 122 | Thousand metric tons | NA |
| 2003 | 94 | Thousand metric tons | -22.95% |
| 2004 | 127.099998474121 | Thousand metric tons | 35.21% |
| 2005 | 107 | Thousand metric tons | -15.81% |
| 2006 | 110 | Thousand metric tons | 2.80% |
| 2007 | 110 | Thousand metric tons | 0.00% |
| 2008 | 110 | Thousand metric tons | 0.00% |
| 2009 | 131 | Thousand metric tons | 19.09% |
| 2010 | 87 | Thousand metric tons | -33.59% |
| 2011 | 100 | Thousand metric tons | 14.94% |
| 2012 | 130 | Thousand metric tons | 30.00% |
| 2013 | 110 | Thousand metric tons | -15.38% |
