Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 287451 | Metric tons | NA |
| 2004 | 306668 | Metric tons | 6.69% |
| 2005 | 268657 | Metric tons | -12.39% |
| 2006 | 206106 | Metric tons | -23.28% |
| 2007 | 185921 | Metric tons | -9.79% |
| 2008 | 140066 | Metric tons | -24.66% |
| 2009 | 152790 | Metric tons | 9.08% |
| 2010 | 143225 | Metric tons | -6.26% |
| 2011 | 134727 | Metric tons | -5.93% |
| 2012 | 139997 | Metric tons | 3.91% |
