Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 2979000 | Metric tons | NA |
| 2003 | 3251100 | Metric tons | 9.13% |
| 2004 | 3776200 | Metric tons | 16.15% |
| 2005 | 3735900 | Metric tons | -1.07% |
| 2006 | 3669000 | Metric tons | -1.79% |
| 2007 | 3724900 | Metric tons | 1.52% |
| 2008 | 3356600 | Metric tons | -9.89% |
| 2009 | 3276900 | Metric tons | -2.37% |
| 2010 | 3330400 | Metric tons | 1.63% |
| 2011 | 3238000 | Metric tons | -2.77% |
| 2012 | 3405100 | Metric tons | 5.16% |
