Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 1340 | Thousand metric tons | NA |
| 2004 | 1580 | Thousand metric tons | 17.91 % |
| 2005 | 1669 | Thousand metric tons | 5.63 % |
| 2006 | 1633 | Thousand metric tons | -2.16 % |
| 2007 | 1660 | Thousand metric tons | 1.65 % |
| 2008 | 1569 | Thousand metric tons | -5.48 % |
| 2009 | 1097 | Thousand metric tons | -30.08 % |
