Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 568000 | Metric tons | NA |
| 2003 | 610000 | Metric tons | 7.39% |
| 2004 | 742000 | Metric tons | 21.64% |
| 2005 | 762000 | Metric tons | 2.70% |
| 2006 | 873000 | Metric tons | 14.57% |
| 2007 | 928000 | Metric tons | 6.30% |
| 2008 | 1070000 | Metric tons | 15.30% |
| 2009 | 1040000 | Metric tons | -2.80% |
| 2010 | 1160000 | Metric tons | 11.54% |
| 2011 | 1270000 | Metric tons | 9.48% |
| 2012 | 1600000 | Metric tons | 25.98% |
