Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 11248 | Thousand metric tons | NA |
| 2004 | 1047.80004882813 | Thousand metric tons | -90.68% |
| 2005 | 1412 | Thousand metric tons | 34.76% |
| 2006 | 1713.59997558594 | Thousand metric tons | 21.36% |
| 2007 | 1439 | Thousand metric tons | -16.02% |
| 2008 | 918.5 | Thousand metric tons | -36.17% |
| 2009 | 860 | Thousand metric tons | -6.37% |
| 2010 | 965 | Thousand metric tons | 12.21% |
| 2011 | 927 | Thousand metric tons | -3.94% |
| 2012 | 927 | Thousand metric tons | 0.00% |
| 2013 | 927 | Thousand metric tons | 0.00% |
