Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 354500 | Metric tons | NA |
| 2004 | 346500 | Metric tons | -2.26% |
| 2005 | 305500 | Metric tons | -11.83% |
| 2006 | 314700 | Metric tons | 3.01% |
| 2007 | 292600 | Metric tons | -7.02% |
| 2008 | 230100 | Metric tons | -21.36% |
| 2009 | 230000 | Metric tons | -0.04% |
| 2010 | 214100 | Metric tons | -6.91% |
| 2011 | 223100 | Metric tons | 4.20% |
| 2012 | 241200 | Metric tons | 8.11% |
| 2013 | 242000 | Metric tons | 0.33% |
