Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 600 | Thousand metric tons | NA |
| 2004 | 650 | Thousand metric tons | 8.33% |
| 2005 | 652 | Thousand metric tons | 0.31% |
| 2006 | 664 | Thousand metric tons | 1.84% |
| 2007 | 679 | Thousand metric tons | 2.26% |
| 2008 | 622 | Thousand metric tons | -8.39% |
| 2009 | 608 | Thousand metric tons | -2.25% |
| 2010 | 667 | Thousand metric tons | 9.70% |
| 2011 | 659 | Thousand metric tons | -1.20% |
| 2012 | 669 | Thousand metric tons | 1.52% |
