Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2005 | 165.893997192383 | Thousand metric tons | NA |
| 2006 | 158.264007568359 | Thousand metric tons | -4.60% |
| 2007 | 282 | Thousand metric tons | 78.18% |
| 2008 | 480.553985595703 | Thousand metric tons | 70.41% |
| 2009 | 428.552001953125 | Thousand metric tons | -10.82% |
| 2010 | 657.89697265625 | Thousand metric tons | 53.52% |
| 2011 | 715.486999511719 | Thousand metric tons | 8.75% |
| 2012 | 770 | Thousand metric tons | 7.62% |
| 2013 | 770 | Thousand metric tons | 0.00% |
