Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 204000 | Metric tons | NA |
| 2003 | 202300 | Metric tons | -0.83% |
| 2004 | 173370 | Metric tons | -14.30% |
| 2005 | 192978 | Metric tons | 11.31% |
| 2006 | 194355 | Metric tons | 0.71% |
| 2007 | 169184 | Metric tons | -12.95% |
| 2008 | 159650 | Metric tons | -5.64% |
| 2009 | 166700 | Metric tons | 4.42% |
| 2010 | 159800 | Metric tons | -4.14% |
| 2011 | 130465 | Metric tons | -18.36% |
| 2012 | 121000 | Metric tons | -7.25% |
