Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 4140 | Thousand metric tons | NA |
| 2004 | 4283.14208984375 | Thousand metric tons | 3.46 % |
| 2005 | 3581.09008789063 | Thousand metric tons | -16.39 % |
| 2006 | 3400 | Thousand metric tons | -5.06 % |
| 2007 | 3240 | Thousand metric tons | -4.71 % |
| 2008 | 2761 | Thousand metric tons | -14.78 % |
| 2009 | 2700 | Thousand metric tons | -2.21 % |
