Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 204027 | Metric tons | NA |
| 2003 | 199020 | Metric tons | -2.45 % |
| 2004 | 177143 | Metric tons | -10.99 % |
| 2005 | 187317 | Metric tons | 5.74 % |
| 2006 | 180144 | Metric tons | -3.83 % |
| 2007 | 180200 | Metric tons | 0.03 % |
| 2008 | 156900 | Metric tons | -12.93 % |
