Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 12063 | Metric tons | NA |
| 2003 | 12217 | Metric tons | 1.28% |
| 2004 | 12202 | Metric tons | -0.12% |
| 2005 | 11739 | Metric tons | -3.79% |
| 2006 | 9528 | Metric tons | -18.83% |
| 2007 | 11835 | Metric tons | 24.21% |
| 2008 | 13000 | Metric tons | 9.84% |
| 2009 | 9500 | Metric tons | -26.92% |
| 2010 | 10400 | Metric tons | 9.47% |
| 2011 | 10725 | Metric tons | 3.13% |
| 2012 | 13667 | Metric tons | 27.43% |
| 2013 | 12000 | Metric tons | -12.20% |
