Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 404.350006103516 | Thousand metric tons | NA |
| 2003 | 596.611999511719 | Thousand metric tons | 47.55 % |
| 2004 | 663.731994628906 | Thousand metric tons | 11.25 % |
| 2005 | 949.60498046875 | Thousand metric tons | 43.07 % |
| 2006 | 667.081970214844 | Thousand metric tons | -29.75 % |
| 2007 | 802.030029296875 | Thousand metric tons | 20.23 % |
| 2008 | 981.932006835938 | Thousand metric tons | 22.43 % |
| 2009 | 1470.18603515625 | Thousand metric tons | 49.72 % |
| 2010 | 3465.89501953125 | Thousand metric tons | 135.75 % |
| 2011 | 7695.5771484375 | Thousand metric tons | 122.04 % |
| 2012 | 8000 | Thousand metric tons | 3.96 % |
