Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 325000 | Metric tons | NA |
| 2004 | 313000 | Metric tons | -3.69% |
| 2005 | 335000 | Metric tons | 7.03% |
| 2006 | 506000 | Metric tons | 51.04% |
| 2007 | 492000 | Metric tons | -2.77% |
| 2008 | 725060 | Metric tons | 47.37% |
| 2009 | 586937 | Metric tons | -19.05% |
| 2010 | 572429 | Metric tons | -2.47% |
| 2011 | 769504 | Metric tons | 34.43% |
| 2012 | 1000000 | Metric tons | 29.95% |
