Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 148 | Thousand metric tons | NA |
| 2003 | 162 | Thousand metric tons | 9.46% |
| 2004 | 61.9000015258789 | Thousand metric tons | -61.79% |
| 2005 | 111.900001525879 | Thousand metric tons | 80.78% |
| 2006 | 140.800003051758 | Thousand metric tons | 25.83% |
| 2007 | 180 | Thousand metric tons | 27.84% |
| 2008 | 269 | Thousand metric tons | 49.44% |
| 2009 | 235 | Thousand metric tons | -12.64% |
| 2010 | 323 | Thousand metric tons | 37.45% |
| 2011 | 426 | Thousand metric tons | 31.89% |
| 2012 | 349 | Thousand metric tons | -18.08% |
