Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 1341 | Thousand metric tons | NA |
| 2004 | 1347 | Thousand metric tons | 0.45 % |
| 2005 | 1304 | Thousand metric tons | -3.19 % |
| 2006 | 1245 | Thousand metric tons | -4.52 % |
| 2007 | 1282 | Thousand metric tons | 2.97 % |
| 2008 | 1151 | Thousand metric tons | -10.22 % |
| 2009 | 1131 | Thousand metric tons | -1.74 % |
