Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 7.64499998092651 | Thousand metric tons | NA |
| 2004 | 9.23400020599365 | Thousand metric tons | 20.78% |
| 2005 | 11.2019996643066 | Thousand metric tons | 21.31% |
| 2006 | 12.2089996337891 | Thousand metric tons | 8.99% |
| 2007 | 7.1269998550415 | Thousand metric tons | -41.63% |
| 2008 | 7.52699995040894 | Thousand metric tons | 5.61% |
| 2009 | 5.46600008010864 | Thousand metric tons | -27.38% |
| 2010 | 4.44899988174438 | Thousand metric tons | -18.61% |
| 2011 | 18.8479995727539 | Thousand metric tons | 323.65% |
| 2012 | 5.35300016403198 | Thousand metric tons | -71.60% |
| 2013 | 6 | Thousand metric tons | 12.09% |
