Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 5033.2001953125 | Thousand metric tons | NA |
| 2004 | 5133 | Thousand metric tons | 1.98% |
| 2005 | 5386 | Thousand metric tons | 4.93% |
| 2006 | 5532.7001953125 | Thousand metric tons | 2.72% |
| 2007 | 5387 | Thousand metric tons | -2.63% |
