Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 1000 | Thousand metric tons | NA |
| 2004 | 1145 | Thousand metric tons | 14.50% |
| 2005 | 825 | Thousand metric tons | -27.95% |
| 2006 | 1040 | Thousand metric tons | 26.06% |
| 2007 | 1090 | Thousand metric tons | 4.81% |
