Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 599 | Thousand metric tons | NA |
| 2004 | 620 | Thousand metric tons | 3.51% |
| 2005 | 652.723999023438 | Thousand metric tons | 5.28% |
| 2006 | 798.984008789063 | Thousand metric tons | 22.41% |
| 2007 | 687.377014160156 | Thousand metric tons | -13.97% |
| 2008 | 763.616027832031 | Thousand metric tons | 11.09% |
| 2009 | 574.935974121094 | Thousand metric tons | -24.71% |
| 2010 | 594.517028808594 | Thousand metric tons | 3.41% |
| 2011 | 813.432983398438 | Thousand metric tons | 36.82% |
| 2012 | 735.4169921875 | Thousand metric tons | -9.59% |
