Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 194.600006103516 | Thousand metric tons | NA |
| 2004 | 216 | Thousand metric tons | 11.00 % |
| 2005 | 243.800003051758 | Thousand metric tons | 12.87 % |
| 2006 | 252.300003051758 | Thousand metric tons | 3.49 % |
| 2007 | 258 | Thousand metric tons | 2.26 % |
| 2008 | 260 | Thousand metric tons | 0.78 % |
| 2009 | 265 | Thousand metric tons | 1.92 % |
