Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 198981 | Metric tons | NA |
| 2004 | 227126 | Metric tons | 14.14 % |
| 2005 | 221300 | Metric tons | -2.57 % |
| 2006 | 235481 | Metric tons | 6.41 % |
| 2007 | 238746 | Metric tons | 1.39 % |
| 2008 | 238800 | Metric tons | 0.02 % |
| 2009 | 239000 | Metric tons | 0.08 % |
