Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 515 | Thousand metric tons | NA |
| 2003 | 500 | Thousand metric tons | -2.91% |
| 2004 | 600 | Thousand metric tons | 20.00% |
| 2005 | 620 | Thousand metric tons | 3.33% |
| 2006 | 620 | Thousand metric tons | 0.00% |
| 2007 | 620 | Thousand metric tons | 0.00% |
| 2008 | 1635 | Thousand metric tons | 163.71% |
| 2009 | 1678 | Thousand metric tons | 2.63% |
| 2010 | 3292 | Thousand metric tons | 96.19% |
| 2011 | 3427 | Thousand metric tons | 4.10% |
| 2012 | 3911 | Thousand metric tons | 14.12% |
