Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 3.36100006103516 | Thousand metric tons | NA |
| 2004 | 2.14199995994568 | Thousand metric tons | -36.27% |
| 2005 | 1.60000002384186 | Thousand metric tons | -25.30% |
| 2006 | 2 | Thousand metric tons | 25.00% |
| 2007 | 2 | Thousand metric tons | 0.00% |
| 2008 | 2 | Thousand metric tons | 0.00% |
| 2009 | 2 | Thousand metric tons | 0.00% |
| 2010 | 0.5 | Thousand metric tons | -75.00% |
| 2011 | 1.0440000295639 | Thousand metric tons | 108.80% |
| 2012 | 1 | Thousand metric tons | -4.21% |
| 2013 | 1 | Thousand metric tons | 0.00% |
