Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 464056 | Metric tons | NA |
| 2004 | 564015 | Metric tons | 21.54% |
| 2005 | 425630 | Metric tons | -24.54% |
| 2006 | 435273 | Metric tons | 2.27% |
| 2007 | 613895 | Metric tons | 41.04% |
| 2008 | 374933 | Metric tons | -38.93% |
| 2009 | 511429 | Metric tons | 36.41% |
| 2010 | 590998 | Metric tons | 15.56% |
| 2011 | 563795 | Metric tons | -4.60% |
| 2012 | 956224 | Metric tons | 69.60% |
| 2013 | 617632 | Metric tons | -35.41% |
