Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 1534 | Thousand metric tons | NA |
| 2004 | 1389 | Thousand metric tons | -9.45% |
| 2005 | 1390 | Thousand metric tons | 0.07% |
| 2006 | 1390 | Thousand metric tons | 0.00% |
| 2007 | 712 | Thousand metric tons | -48.78% |
| 2008 | 1065 | Thousand metric tons | 49.58% |
| 2009 | 1062 | Thousand metric tons | -0.28% |
| 2010 | 1121 | Thousand metric tons | 5.56% |
