Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 1340 | Thousand metric tons | NA |
| 2004 | 1580 | Thousand metric tons | 17.91% |
| 2005 | 1669 | Thousand metric tons | 5.63% |
| 2006 | 1633 | Thousand metric tons | -2.16% |
| 2007 | 1660 | Thousand metric tons | 1.65% |
| 2008 | 1569 | Thousand metric tons | -5.48% |
| 2009 | 1097 | Thousand metric tons | -30.08% |
| 2010 | 1270 | Thousand metric tons | 15.77% |
| 2011 | 300 | Thousand metric tons | -76.38% |
| 2012 | 510 | Thousand metric tons | 70.00% |
