Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 3378 | Thousand metric tons | NA |
| 2003 | 3654 | Thousand metric tons | 8.17 % |
| 2004 | 3811 | Thousand metric tons | 4.30 % |
| 2005 | 3480.94897460938 | Thousand metric tons | -8.66 % |
| 2006 | 3597.96508789063 | Thousand metric tons | 3.36 % |
| 2007 | 3524.39111328125 | Thousand metric tons | -2.04 % |
| 2008 | 3500 | Thousand metric tons | -0.69 % |
