Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 1050 | Thousand metric tons | NA |
| 2004 | 1167 | Thousand metric tons | 11.14 % |
| 2005 | 1189 | Thousand metric tons | 1.89 % |
| 2006 | 1177 | Thousand metric tons | -1.01 % |
| 2007 | 1192 | Thousand metric tons | 1.27 % |
| 2008 | 1190 | Thousand metric tons | -0.17 % |
| 2009 | 1200 | Thousand metric tons | 0.84 % |
