Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 471 | Thousand metric tons | NA |
| 2003 | 572 | Thousand metric tons | 21.44 % |
| 2004 | 518.9990234375 | Thousand metric tons | -9.27 % |
| 2005 | 543.072021484375 | Thousand metric tons | 4.64 % |
| 2006 | 570.031005859375 | Thousand metric tons | 4.96 % |
| 2007 | 608.192016601563 | Thousand metric tons | 6.69 % |
| 2008 | 675.788024902344 | Thousand metric tons | 11.11 % |
