Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 53 | Thousand metric tons | NA |
| 2004 | 59 | Thousand metric tons | 11.32% |
| 2005 | 62.1319999694824 | Thousand metric tons | 5.31% |
| 2006 | 62.9480018615723 | Thousand metric tons | 1.31% |
| 2007 | 63 | Thousand metric tons | 0.08% |
| 2008 | 128.535995483398 | Thousand metric tons | 104.03% |
| 2009 | 80.806999206543 | Thousand metric tons | -37.13% |
| 2010 | 91.7099990844727 | Thousand metric tons | 13.49% |
| 2011 | 84.2310028076172 | Thousand metric tons | -8.16% |
| 2012 | 85 | Thousand metric tons | 0.91% |
