Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 1584 | Thousand metric tons | NA |
| 2003 | 1863 | Thousand metric tons | 17.61% |
| 2004 | 2635 | Thousand metric tons | 41.44% |
| 2005 | 2145 | Thousand metric tons | -18.60% |
| 2006 | 2200 | Thousand metric tons | 2.56% |
| 2007 | 2200 | Thousand metric tons | 0.00% |
| 2008 | 2600 | Thousand metric tons | 18.18% |
| 2009 | 2000 | Thousand metric tons | -23.08% |
| 2010 | 2000 | Thousand metric tons | 0.00% |
| 2011 | 2250 | Thousand metric tons | 12.50% |
| 2012 | 2250 | Thousand metric tons | 0.00% |
