Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 45649 | Metric tons | NA |
| 2004 | 47945 | Metric tons | 5.03% |
| 2005 | 52813 | Metric tons | 10.15% |
| 2006 | 64787 | Metric tons | 22.67% |
| 2007 | 63098 | Metric tons | -2.61% |
| 2008 | 60088 | Metric tons | -4.77% |
| 2009 | 38000 | Metric tons | -36.76% |
| 2010 | 42000 | Metric tons | 10.53% |
| 2011 | 40000 | Metric tons | -4.76% |
| 2012 | 40000 | Metric tons | 0.00% |
