Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 2175 | Metric tons | NA |
| 2004 | 2362 | Metric tons | 8.60% |
| 2005 | 2582 | Metric tons | 9.31% |
| 2006 | 3320 | Metric tons | 28.58% |
| 2007 | 2846 | Metric tons | -14.28% |
| 2008 | 3090 | Metric tons | 8.57% |
| 2009 | 2500 | Metric tons | -19.09% |
| 2010 | 4166 | Metric tons | 66.64% |
| 2011 | 3005 | Metric tons | -27.87% |
| 2012 | 3904 | Metric tons | 29.92% |
| 2013 | 4000 | Metric tons | 2.46% |
