Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 194.600006103516 | Thousand metric tons | NA |
| 2004 | 216 | Thousand metric tons | 11.00% |
| 2005 | 243.800003051758 | Thousand metric tons | 12.87% |
| 2006 | 252.300003051758 | Thousand metric tons | 3.49% |
| 2007 | 258 | Thousand metric tons | 2.26% |
| 2008 | 260 | Thousand metric tons | 0.78% |
| 2009 | 265 | Thousand metric tons | 1.92% |
| 2010 | 266 | Thousand metric tons | 0.38% |
| 2011 | 265 | Thousand metric tons | -0.38% |
| 2012 | 265 | Thousand metric tons | 0.00% |
| 2013 | 320 | Thousand metric tons | 20.75% |
