Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 3892 | Thousand metric tons | NA |
| 2004 | 3765 | Thousand metric tons | -3.26 % |
| 2005 | 3618 | Thousand metric tons | -3.90 % |
| 2006 | 4145 | Thousand metric tons | 14.57 % |
| 2007 | 4012 | Thousand metric tons | -3.21 % |
| 2008 | 3529 | Thousand metric tons | -12.04 % |
| 2009 | 3019 | Thousand metric tons | -14.45 % |
