Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 131705 | Metric tons | NA |
| 2003 | 131600 | Metric tons | -0.08% |
| 2004 | 132000 | Metric tons | 0.30% |
| 2005 | 126547 | Metric tons | -4.13% |
| 2006 | 129693 | Metric tons | 2.49% |
| 2007 | 130160 | Metric tons | 0.36% |
| 2008 | 126796 | Metric tons | -2.58% |
| 2009 | 129800 | Metric tons | 2.37% |
| 2010 | 124985 | Metric tons | -3.71% |
| 2011 | 121590 | Metric tons | -2.72% |
| 2012 | 121700 | Metric tons | 0.09% |
