Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 493000 | Metric tons | NA |
| 2004 | 508000 | Metric tons | 3.04% |
| 2005 | 508000 | Metric tons | 0.00% |
| 2006 | 454000 | Metric tons | -10.63% |
| 2007 | 409000 | Metric tons | -9.91% |
| 2008 | 434000 | Metric tons | 6.11% |
| 2009 | 348000 | Metric tons | -19.82% |
| 2010 | 414000 | Metric tons | 18.97% |
| 2011 | 420000 | Metric tons | 1.45% |
| 2012 | 393000 | Metric tons | -6.43% |
| 2013 | 419000 | Metric tons | 6.62% |
