Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 135.356002807617 | Thousand metric tons | NA |
| 2004 | 119.960998535156 | Thousand metric tons | -11.37% |
| 2005 | 116 | Thousand metric tons | -3.30% |
| 2006 | 108 | Thousand metric tons | -6.90% |
| 2007 | 112 | Thousand metric tons | 3.70% |
| 2008 | 98.9000015258789 | Thousand metric tons | -11.70% |
| 2009 | 3085 | Thousand metric tons | 3,019.31% |
| 2010 | 2868 | Thousand metric tons | -7.03% |
| 2011 | 2934 | Thousand metric tons | 2.30% |
| 2012 | 3048 | Thousand metric tons | 3.89% |
| 2013 | 3000 | Thousand metric tons | -1.57% |
