Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 40745 | Metric tons | NA |
| 2004 | 44207 | Metric tons | 8.50 % |
| 2005 | 42087 | Metric tons | -4.80 % |
| 2006 | 45169 | Metric tons | 7.32 % |
| 2007 | 44000 | Metric tons | -2.59 % |
| 2008 | 43000 | Metric tons | -2.27 % |
| 2009 | 42000 | Metric tons | -2.33 % |
