Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 23287 | Thousand metric tons | NA |
| 2003 | 24147 | Thousand metric tons | 3.69 % |
| 2004 | 25380 | Thousand metric tons | 5.11 % |
| 2005 | 26063.853515625 | Thousand metric tons | 2.69 % |
| 2006 | 27056 | Thousand metric tons | 3.81 % |
| 2007 | 30368.771484375 | Thousand metric tons | 12.24 % |
| 2008 | 31822.84765625 | Thousand metric tons | 4.79 % |
