Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 45649 | Metric tons | NA |
| 2004 | 47945 | Metric tons | 5.03 % |
| 2005 | 52813 | Metric tons | 10.15 % |
| 2006 | 64787 | Metric tons | 22.67 % |
| 2007 | 63098 | Metric tons | -2.61 % |
| 2008 | 60088 | Metric tons | -4.77 % |
| 2009 | 60000 | Metric tons | -0.15 % |
