Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 200500 | Metric tons | NA |
| 2004 | 220000 | Metric tons | 9.73% |
| 2005 | 200000 | Metric tons | -9.09% |
| 2006 | 200000 | Metric tons | 0.00% |
| 2007 | 180000 | Metric tons | -10.00% |
| 2008 | 160000 | Metric tons | -11.11% |
| 2009 | 150000 | Metric tons | -6.25% |
| 2010 | 100000 | Metric tons | -33.33% |
| 2011 | 50000 | Metric tons | -50.00% |
