Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 2497 | Metric tons | NA |
| 2004 | 2233 | Metric tons | -10.57% |
| 2005 | 2297 | Metric tons | 2.87% |
| 2006 | 2287 | Metric tons | -0.44% |
| 2007 | 1933 | Metric tons | -15.48% |
| 2008 | 2116 | Metric tons | 9.47% |
| 2009 | 1824 | Metric tons | -13.80% |
| 2010 | 2142 | Metric tons | 17.43% |
| 2011 | 1755 | Metric tons | -18.07% |
| 2012 | 1855 | Metric tons | 5.70% |
| 2013 | 1826 | Metric tons | -1.56% |
