Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 286.022003173828 | Thousand metric tons | NA |
| 2004 | 270.600006103516 | Thousand metric tons | -5.39% |
| 2005 | 272.399993896484 | Thousand metric tons | 0.67% |
| 2006 | 319.5 | Thousand metric tons | 17.29% |
| 2007 | 398 | Thousand metric tons | 24.57% |
| 2008 | 787 | Thousand metric tons | 97.74% |
| 2009 | 804.60498046875 | Thousand metric tons | 2.24% |
| 2010 | 805.802978515625 | Thousand metric tons | 0.15% |
| 2011 | 780.85302734375 | Thousand metric tons | -3.10% |
| 2012 | 820 | Thousand metric tons | 5.01% |
| 2013 | 800 | Thousand metric tons | -2.44% |
