Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 121000 | Metric tons | NA |
| 2003 | 130000 | Metric tons | 7.44% |
| 2004 | 140000 | Metric tons | 7.69% |
| 2005 | 150000 | Metric tons | 7.14% |
| 2006 | 208000 | Metric tons | 38.67% |
| 2007 | 241000 | Metric tons | 15.87% |
| 2008 | 241000 | Metric tons | 0.00% |
| 2009 | 256000 | Metric tons | 6.22% |
| 2010 | 249000 | Metric tons | -2.73% |
| 2011 | 249000 | Metric tons | 0.00% |
| 2012 | 233000 | Metric tons | -6.43% |
