Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 1300 | Thousand metric tons | NA |
| 2004 | 994 | Thousand metric tons | -23.54% |
| 2005 | 952 | Thousand metric tons | -4.23% |
| 2006 | 1093 | Thousand metric tons | 14.81% |
| 2007 | 1193 | Thousand metric tons | 9.15% |
| 2008 | 690 | Thousand metric tons | -42.16% |
| 2009 | 493 | Thousand metric tons | -28.55% |
| 2010 | 696 | Thousand metric tons | 41.18% |
| 2011 | 360 | Thousand metric tons | -48.28% |
| 2012 | 400 | Thousand metric tons | 11.11% |
