Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 109506 | Metric tons | NA |
| 2004 | 93624 | Metric tons | -14.50 % |
| 2005 | 88591 | Metric tons | -5.38 % |
| 2006 | 85524 | Metric tons | -3.46 % |
| 2007 | 88265 | Metric tons | 3.20 % |
| 2008 | 78941 | Metric tons | -10.56 % |
| 2009 | 75000 | Metric tons | -4.99 % |
