Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 1064 | Thousand metric tons | NA |
| 2004 | 1114 | Thousand metric tons | 4.70 % |
| 2005 | 1093 | Thousand metric tons | -1.89 % |
| 2006 | 1159 | Thousand metric tons | 6.04 % |
| 2007 | 1327 | Thousand metric tons | 14.50 % |
