Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 18364 | Metric tons | NA |
| 2003 | 20414 | Metric tons | 11.16% |
| 2004 | 15984 | Metric tons | -21.70% |
| 2005 | 16323 | Metric tons | 2.12% |
| 2006 | 17161 | Metric tons | 5.13% |
| 2007 | 22862 | Metric tons | 33.22% |
| 2008 | 21235 | Metric tons | -7.12% |
| 2009 | 49060 | Metric tons | 131.03% |
| 2010 | 58412 | Metric tons | 19.06% |
| 2011 | 63835 | Metric tons | 9.28% |
| 2012 | 65444 | Metric tons | 2.52% |
