Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 70739 | Metric tons | NA |
| 2004 | 76332 | Metric tons | 7.91 % |
| 2005 | 77494 | Metric tons | 1.52 % |
| 2006 | 76194 | Metric tons | -1.68 % |
| 2007 | 77163 | Metric tons | 1.27 % |
| 2008 | 76200 | Metric tons | -1.25 % |
| 2009 | 76200 | Metric tons | 0.00 % |
