Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 431 | Thousand metric tons | NA |
| 2004 | 509 | Thousand metric tons | 18.10% |
| 2005 | 639 | Thousand metric tons | 25.54% |
| 2006 | 577 | Thousand metric tons | -9.70% |
| 2007 | 641 | Thousand metric tons | 11.09% |
| 2008 | 632 | Thousand metric tons | -1.40% |
| 2009 | 593.869018554688 | Thousand metric tons | -6.03% |
| 2010 | 671.585021972656 | Thousand metric tons | 13.09% |
| 2011 | 745.971984863281 | Thousand metric tons | 11.08% |
| 2012 | 758.841003417969 | Thousand metric tons | 1.73% |
| 2013 | 760 | Thousand metric tons | 0.15% |
