Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 264 | Thousand metric tons | NA |
| 2003 | 197 | Thousand metric tons | -25.38% |
| 2004 | 2300.70288085938 | Thousand metric tons | 1,067.87% |
| 2005 | 3500.86401367188 | Thousand metric tons | 52.16% |
| 2006 | 4369.77099609375 | Thousand metric tons | 24.82% |
| 2007 | 3241.17700195313 | Thousand metric tons | -25.83% |
| 2008 | 3000 | Thousand metric tons | -7.44% |
| 2009 | 4369.5888671875 | Thousand metric tons | 45.65% |
| 2010 | 6321.89111328125 | Thousand metric tons | 44.68% |
| 2011 | 5723.43896484375 | Thousand metric tons | -9.47% |
| 2012 | 8248.4462890625 | Thousand metric tons | 44.12% |
| 2013 | 8300 | Thousand metric tons | 0.63% |
