Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 800 | Thousand metric tons | NA |
| 2003 | 800 | Thousand metric tons | 0.00% |
| 2004 | 800 | Thousand metric tons | 0.00% |
| 2005 | 800 | Thousand metric tons | 0.00% |
| 2006 | 800 | Thousand metric tons | 0.00% |
| 2007 | 800 | Thousand metric tons | 0.00% |
| 2008 | 1265 | Thousand metric tons | 58.13% |
| 2009 | 1179 | Thousand metric tons | -6.80% |
| 2010 | 1185 | Thousand metric tons | 0.51% |
| 2011 | 1160 | Thousand metric tons | -2.11% |
| 2012 | 1605 | Thousand metric tons | 38.36% |
