Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 578 | Thousand metric tons | NA |
| 2004 | 573.221008300781 | Thousand metric tons | -0.83% |
| 2005 | 489 | Thousand metric tons | -14.69% |
| 2006 | 525 | Thousand metric tons | 7.36% |
| 2007 | 889 | Thousand metric tons | 69.33% |
| 2008 | 918 | Thousand metric tons | 3.26% |
| 2009 | 1108 | Thousand metric tons | 20.70% |
| 2010 | 1300 | Thousand metric tons | 17.33% |
| 2011 | 1800 | Thousand metric tons | 38.46% |
| 2012 | 2000 | Thousand metric tons | 11.11% |
