Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 3600000 | Metric tons | NA |
| 2004 | 3900000 | Metric tons | 8.33% |
| 2005 | 4200000 | Metric tons | 7.69% |
| 2006 | 4400000 | Metric tons | 4.76% |
| 2007 | 4400000 | Metric tons | 0.00% |
| 2008 | 4600000 | Metric tons | 4.55% |
| 2009 | 3000000 | Metric tons | -34.78% |
| 2010 | 4000000 | Metric tons | 33.33% |
| 2011 | 4100000 | Metric tons | 2.50% |
| 2012 | 4200000 | Metric tons | 2.44% |
