Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 18 | Thousand metric tons | NA |
| 2003 | 18 | Thousand metric tons | 0.00% |
| 2004 | 17.7000007629395 | Thousand metric tons | -1.67% |
| 2005 | 17.4169998168945 | Thousand metric tons | -1.60% |
| 2006 | 13.0430002212524 | Thousand metric tons | -25.11% |
| 2007 | 4.59999990463257 | Thousand metric tons | -64.73% |
| 2008 | 4.59999990463257 | Thousand metric tons | 0.00% |
| 2009 | 19.7369995117188 | Thousand metric tons | 329.07% |
| 2010 | 7.55900001525879 | Thousand metric tons | -61.70% |
| 2011 | 6.05800008773804 | Thousand metric tons | -19.86% |
| 2012 | 6 | Thousand metric tons | -0.96% |
| 2013 | 6 | Thousand metric tons | 0.00% |
