Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 782.31201171875 | Thousand metric tons | NA |
| 2004 | 1025.50305175781 | Thousand metric tons | 31.09% |
| 2005 | 583 | Thousand metric tons | -43.15% |
| 2006 | 250 | Thousand metric tons | -57.12% |
| 2007 | 551 | Thousand metric tons | 120.40% |
| 2008 | 734 | Thousand metric tons | 33.21% |
| 2009 | 657 | Thousand metric tons | -10.49% |
| 2010 | 660 | Thousand metric tons | 0.46% |
| 2011 | 660 | Thousand metric tons | 0.00% |
| 2012 | 660 | Thousand metric tons | 0.00% |
| 2013 | 660 | Thousand metric tons | 0.00% |
