Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 2000 | Thousand metric tons | NA |
| 2004 | 2000 | Thousand metric tons | 0.00% |
| 2005 | 459.779998779297 | Thousand metric tons | -77.01% |
| 2006 | 465.358001708984 | Thousand metric tons | 1.21% |
| 2007 | 490.707000732422 | Thousand metric tons | 5.45% |
| 2008 | 612.202026367188 | Thousand metric tons | 24.76% |
| 2009 | 725.442993164063 | Thousand metric tons | 18.50% |
| 2010 | 733.697998046875 | Thousand metric tons | 1.14% |
| 2011 | 800.835998535156 | Thousand metric tons | 9.15% |
| 2012 | 800 | Thousand metric tons | -0.10% |
| 2013 | 800 | Thousand metric tons | 0.00% |
