Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 147000 | Metric tons | NA |
| 2004 | 104000 | Metric tons | -29.25% |
| 2005 | 122041 | Metric tons | 17.35% |
| 2006 | 100000 | Metric tons | -18.06% |
| 2007 | 80000 | Metric tons | -20.00% |
| 2008 | 50000 | Metric tons | -37.50% |
| 2009 | 4971 | Metric tons | -90.06% |
| 2010 | 2400 | Metric tons | -51.72% |
