Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 9941 | Thousand metric tons | NA |
| 2003 | 11265 | Thousand metric tons | 13.32% |
| 2004 | 11483 | Thousand metric tons | 1.94% |
| 2005 | 11687 | Thousand metric tons | 1.78% |
| 2006 | 10983 | Thousand metric tons | -6.02% |
| 2007 | 10916.4365234375 | Thousand metric tons | -0.61% |
| 2008 | 11688.107421875 | Thousand metric tons | 7.07% |
| 2009 | 11677.494140625 | Thousand metric tons | -0.09% |
| 2010 | 13998.2734375 | Thousand metric tons | 19.87% |
| 2011 | 14482.0498046875 | Thousand metric tons | 3.46% |
| 2012 | 14500 | Thousand metric tons | 0.12% |
