Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 350 | Thousand metric tons | NA |
| 2003 | 1460 | Thousand metric tons | 317.14% |
| 2004 | 1058 | Thousand metric tons | -27.53% |
| 2005 | 1460 | Thousand metric tons | 38.00% |
| 2006 | 1033.10705566406 | Thousand metric tons | -29.24% |
| 2007 | 1198.30297851563 | Thousand metric tons | 15.99% |
| 2008 | 1672 | Thousand metric tons | 39.53% |
| 2009 | 1757 | Thousand metric tons | 5.08% |
| 2010 | 1610 | Thousand metric tons | -8.37% |
| 2011 | 1650 | Thousand metric tons | 2.48% |
| 2012 | 1700 | Thousand metric tons | 3.03% |
| 2013 | 1700 | Thousand metric tons | 0.00% |
