Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 101.199996948242 | Thousand metric tons | NA |
| 2004 | 101.400001525879 | Thousand metric tons | 0.20% |
| 2005 | 102.300003051758 | Thousand metric tons | 0.89% |
| 2006 | 101.199996948242 | Thousand metric tons | -1.08% |
| 2007 | 98 | Thousand metric tons | -3.16% |
| 2008 | 112 | Thousand metric tons | 14.29% |
| 2009 | 69.7080001831055 | Thousand metric tons | -37.76% |
| 2010 | 93 | Thousand metric tons | 33.41% |
| 2011 | 111 | Thousand metric tons | 19.35% |
| 2012 | 129 | Thousand metric tons | 16.22% |
| 2013 | 131 | Thousand metric tons | 1.55% |
