Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 1955 | Thousand metric tons | NA |
| 2004 | 1950 | Thousand metric tons | -0.26 % |
| 2005 | 1749 | Thousand metric tons | -10.31 % |
| 2006 | 1936 | Thousand metric tons | 10.69 % |
| 2007 | 2143 | Thousand metric tons | 10.69 % |
| 2008 | 1951.59997558594 | Thousand metric tons | -8.93 % |
| 2009 | 1950 | Thousand metric tons | -0.08 % |
