Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 37344 | Metric tons | NA |
| 2004 | 30373 | Metric tons | -18.67% |
| 2005 | 25032 | Metric tons | -17.58% |
| 2006 | 15085 | Metric tons | -39.74% |
| 2007 | 22000 | Metric tons | 45.84% |
| 2008 | 20000 | Metric tons | -9.09% |
