Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 230 | Thousand metric tons | NA |
| 2003 | 350 | Thousand metric tons | 52.17% |
| 2004 | 390 | Thousand metric tons | 11.43% |
| 2005 | 435 | Thousand metric tons | 11.54% |
| 2006 | 650 | Thousand metric tons | 49.43% |
| 2007 | 650 | Thousand metric tons | 0.00% |
| 2008 | 560 | Thousand metric tons | -13.85% |
| 2009 | 880 | Thousand metric tons | 57.14% |
| 2010 | 1127 | Thousand metric tons | 28.07% |
| 2011 | 1200 | Thousand metric tons | 6.48% |
| 2012 | 1200 | Thousand metric tons | 0.00% |
