Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 10948 | Thousand metric tons | NA |
| 2003 | 11653 | Thousand metric tons | 6.44% |
| 2004 | 12566.2646484375 | Thousand metric tons | 7.84% |
| 2005 | 12646.22265625 | Thousand metric tons | 0.64% |
| 2006 | 14688.3525390625 | Thousand metric tons | 16.15% |
| 2007 | 17119.935546875 | Thousand metric tons | 16.55% |
| 2008 | 17207 | Thousand metric tons | 0.51% |
| 2009 | 15422 | Thousand metric tons | -10.37% |
| 2010 | 15812 | Thousand metric tons | 2.53% |
| 2011 | 18993 | Thousand metric tons | 20.12% |
| 2012 | 15919 | Thousand metric tons | -16.18% |
