Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 1590 | Metric tons | NA |
| 2004 | 1615 | Metric tons | 1.57% |
| 2005 | 1653 | Metric tons | 2.35% |
| 2006 | 1401 | Metric tons | -15.25% |
| 2007 | 1617 | Metric tons | 15.42% |
| 2008 | 1550 | Metric tons | -4.14% |
| 2009 | 1510 | Metric tons | -2.58% |
| 2010 | 1464 | Metric tons | -3.05% |
| 2011 | 1485 | Metric tons | 1.43% |
| 2012 | 1624 | Metric tons | 9.36% |
| 2013 | 1489 | Metric tons | -8.31% |
