Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 216000 | Metric tons | NA |
| 2004 | 222000 | Metric tons | 2.78 % |
| 2005 | 226000 | Metric tons | 1.80 % |
| 2006 | 243000 | Metric tons | 7.52 % |
