Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 198981 | Metric tons | NA |
| 2004 | 227126 | Metric tons | 14.14% |
| 2005 | 221300 | Metric tons | -2.57% |
| 2006 | 235481 | Metric tons | 6.41% |
| 2007 | 238746 | Metric tons | 1.39% |
| 2008 | 238800 | Metric tons | 0.02% |
| 2009 | 264243 | Metric tons | 10.65% |
| 2010 | 531693 | Metric tons | 101.21% |
| 2011 | 566267 | Metric tons | 6.50% |
| 2012 | 512975 | Metric tons | -9.41% |
| 2013 | 513000 | Metric tons | 0.00% |
