Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 100000 | Metric tons | NA |
| 2004 | 78000 | Metric tons | -22.00% |
| 2005 | 81000 | Metric tons | 3.85% |
| 2006 | 86000 | Metric tons | 6.17% |
| 2007 | 91000 | Metric tons | 5.81% |
| 2008 | 92000 | Metric tons | 1.10% |
