Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 57000 | Metric tons | NA |
| 2004 | 61000 | Metric tons | 7.02 % |
| 2005 | 62000 | Metric tons | 1.64 % |
| 2006 | 50000 | Metric tons | -19.35 % |
| 2007 | 55000 | Metric tons | 10.00 % |
| 2008 | 50000 | Metric tons | -9.09 % |
| 2009 | 50000 | Metric tons | 0.00 % |
