Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 1882 | Thousand metric tons | NA |
| 2004 | 1900 | Thousand metric tons | 0.96 % |
| 2005 | 1920 | Thousand metric tons | 1.05 % |
| 2006 | 1892 | Thousand metric tons | -1.46 % |
| 2007 | 1900 | Thousand metric tons | 0.42 % |
