Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 32711 | Metric tons | NA |
| 2003 | 26275 | Metric tons | -19.68% |
| 2004 | 103153 | Metric tons | 292.59% |
| 2005 | 133325 | Metric tons | 29.25% |
| 2006 | 147836 | Metric tons | 10.88% |
| 2007 | 205728 | Metric tons | 39.16% |
| 2008 | 218295 | Metric tons | 6.11% |
| 2009 | 211692 | Metric tons | -3.02% |
| 2010 | 213548 | Metric tons | 0.88% |
| 2011 | 218670 | Metric tons | 2.40% |
| 2012 | 213800 | Metric tons | -2.23% |
