Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 1463 | Thousand metric tons | NA |
| 2003 | 1658 | Thousand metric tons | 13.33% |
| 2004 | 1789.10205078125 | Thousand metric tons | 7.91% |
| 2005 | 2123.25610351563 | Thousand metric tons | 18.68% |
| 2006 | 2174.09008789063 | Thousand metric tons | 2.39% |
| 2007 | 2545.66088867188 | Thousand metric tons | 17.09% |
| 2008 | 2829 | Thousand metric tons | 11.13% |
| 2009 | 3320 | Thousand metric tons | 17.36% |
| 2010 | 3710 | Thousand metric tons | 11.75% |
| 2011 | 4478 | Thousand metric tons | 20.70% |
| 2012 | 4640 | Thousand metric tons | 3.62% |
