Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 490 | Thousand metric tons | NA |
| 2003 | 600 | Thousand metric tons | 22.45% |
| 2004 | 550 | Thousand metric tons | -8.33% |
| 2005 | 490 | Thousand metric tons | -10.91% |
| 2006 | 600 | Thousand metric tons | 22.45% |
| 2007 | 800 | Thousand metric tons | 33.33% |
| 2008 | 744 | Thousand metric tons | -7.00% |
| 2009 | 777 | Thousand metric tons | 4.44% |
| 2010 | 884 | Thousand metric tons | 13.77% |
| 2011 | 976 | Thousand metric tons | 10.41% |
| 2012 | 1184 | Thousand metric tons | 21.31% |
