Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 987.869018554688 | Thousand metric tons | NA |
| 2004 | 1137 | Thousand metric tons | 15.10% |
| 2005 | 1074 | Thousand metric tons | -5.54% |
| 2006 | 1115 | Thousand metric tons | 3.82% |
| 2007 | 1147 | Thousand metric tons | 2.87% |
| 2008 | 1109 | Thousand metric tons | -3.31% |
| 2009 | 923 | Thousand metric tons | -16.77% |
| 2010 | 635 | Thousand metric tons | -31.20% |
| 2011 | 1072 | Thousand metric tons | 68.82% |
| 2012 | 1065 | Thousand metric tons | -0.65% |
