Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 12.8249998092651 | Thousand metric tons | NA |
| 2004 | 11.1719999313354 | Thousand metric tons | -12.89 % |
| 2005 | 14.2609996795654 | Thousand metric tons | 27.65 % |
| 2006 | 9.56700038909912 | Thousand metric tons | -32.91 % |
| 2007 | 14.460000038147 | Thousand metric tons | 51.14 % |
| 2008 | 14.8179998397827 | Thousand metric tons | 2.48 % |
| 2009 | 6.79199981689453 | Thousand metric tons | -54.16 % |
