Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 129589 | Metric tons | NA |
| 2003 | 120800 | Metric tons | -6.78% |
| 2004 | 87000 | Metric tons | -27.98% |
| 2005 | 88600 | Metric tons | 1.84% |
| 2006 | 89500 | Metric tons | 1.02% |
| 2007 | 97000 | Metric tons | 8.38% |
| 2008 | 108700 | Metric tons | 12.06% |
| 2009 | 107600 | Metric tons | -1.01% |
| 2010 | 102600 | Metric tons | -4.65% |
| 2011 | 96600 | Metric tons | -5.85% |
| 2012 | 77000 | Metric tons | -20.29% |
