Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 2.27099990844727 | Thousand metric tons | NA |
| 2004 | 0.869000017642975 | Thousand metric tons | -61.73% |
| 2005 | 0.551999986171722 | Thousand metric tons | -36.48% |
| 2006 | 0.688000023365021 | Thousand metric tons | 24.64% |
| 2007 | 1.54499995708466 | Thousand metric tons | 124.56% |
| 2008 | 1.41499996185303 | Thousand metric tons | -8.41% |
| 2009 | 1.94700002670288 | Thousand metric tons | 37.60% |
| 2010 | 1.21800005435944 | Thousand metric tons | -37.44% |
| 2011 | 1.96800005435944 | Thousand metric tons | 61.58% |
| 2012 | 2.46099996566772 | Thousand metric tons | 25.05% |
| 2013 | 2 | Thousand metric tons | -18.73% |
