Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 54 | Thousand metric tons | NA |
| 2003 | 25 | Thousand metric tons | -53.70% |
| 2004 | 121.05899810791 | Thousand metric tons | 384.24% |
| 2005 | 143.84700012207 | Thousand metric tons | 18.82% |
| 2006 | 154.990005493164 | Thousand metric tons | 7.75% |
| 2007 | 157.199996948242 | Thousand metric tons | 1.43% |
| 2008 | 94 | Thousand metric tons | -40.20% |
| 2009 | 71 | Thousand metric tons | -24.47% |
| 2010 | 72 | Thousand metric tons | 1.41% |
| 2011 | 81 | Thousand metric tons | 12.50% |
| 2012 | 109 | Thousand metric tons | 34.57% |
