Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 92800 | Metric tons | NA |
| 2003 | 91700 | Metric tons | -1.19% |
| 2004 | 94000 | Metric tons | 2.51% |
| 2005 | 95000 | Metric tons | 1.06% |
| 2006 | 110000 | Metric tons | 15.79% |
| 2007 | 109600 | Metric tons | -0.36% |
| 2008 | 105000 | Metric tons | -4.20% |
| 2009 | 105000 | Metric tons | 0.00% |
| 2010 | 105000 | Metric tons | 0.00% |
| 2011 | 105000 | Metric tons | 0.00% |
| 2012 | 107900 | Metric tons | 2.76% |
