Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 31 | Thousand metric tons | NA |
| 2004 | 33 | Thousand metric tons | 6.45% |
| 2005 | 14 | Thousand metric tons | -57.58% |
| 2006 | 9 | Thousand metric tons | -35.71% |
| 2007 | 21.3999996185303 | Thousand metric tons | 137.78% |
| 2008 | 29.1000003814697 | Thousand metric tons | 35.98% |
| 2009 | 16.3999996185303 | Thousand metric tons | -43.64% |
| 2010 | 11.1000003814697 | Thousand metric tons | -32.32% |
| 2011 | 20.3999996185303 | Thousand metric tons | 83.78% |
| 2012 | 24.7000007629395 | Thousand metric tons | 21.08% |
| 2013 | 26.1000003814697 | Thousand metric tons | 5.67% |
