Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 76200 | Metric tons | NA |
| 2003 | 96000 | Metric tons | 25.98% |
| 2004 | 90600 | Metric tons | -5.62% |
| 2005 | 97800 | Metric tons | 7.95% |
| 2006 | 86746 | Metric tons | -11.30% |
| 2007 | 62905 | Metric tons | -27.48% |
| 2008 | 57220 | Metric tons | -9.04% |
| 2009 | 54602 | Metric tons | -4.58% |
| 2010 | 76500 | Metric tons | 40.10% |
| 2011 | 83000 | Metric tons | 8.50% |
| 2012 | 83000 | Metric tons | 0.00% |
