Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 200 | Thousand metric tons | NA |
| 2004 | 247 | Thousand metric tons | 23.50% |
| 2005 | 252.300003051758 | Thousand metric tons | 2.15% |
| 2006 | 250.300003051758 | Thousand metric tons | -0.79% |
| 2007 | 242.100006103516 | Thousand metric tons | -3.28% |
| 2008 | 242.5 | Thousand metric tons | 0.17% |
| 2009 | 257.600006103516 | Thousand metric tons | 6.23% |
| 2010 | 253.300003051758 | Thousand metric tons | -1.67% |
| 2011 | 244.100006103516 | Thousand metric tons | -3.63% |
| 2012 | 248 | Thousand metric tons | 1.60% |
| 2013 | 250 | Thousand metric tons | 0.81% |
