Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 214560 | Thousand metric tons | NA |
| 2003 | 230707 | Thousand metric tons | 7.53% |
| 2004 | 261675 | Thousand metric tons | 13.42% |
| 2005 | 281462.09375 | Thousand metric tons | 7.56% |
| 2006 | 317800.21875 | Thousand metric tons | 12.91% |
| 2007 | 354674.375 | Thousand metric tons | 11.60% |
| 2008 | 350707 | Thousand metric tons | -1.12% |
| 2009 | 298528 | Thousand metric tons | -14.88% |
| 2010 | 372120.09375 | Thousand metric tons | 24.65% |
| 2011 | 398130.8125 | Thousand metric tons | 6.99% |
| 2012 | 398150 | Thousand metric tons | 0.00% |
