Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 182802 | Metric tons | NA |
| 2004 | 196893 | Metric tons | 7.71% |
| 2005 | 209801 | Metric tons | 6.56% |
| 2006 | 197765 | Metric tons | -5.74% |
| 2007 | 198526 | Metric tons | 0.38% |
| 2008 | 199764 | Metric tons | 0.62% |
| 2009 | 193334 | Metric tons | -3.22% |
| 2010 | 199285 | Metric tons | 3.08% |
| 2011 | 170571 | Metric tons | -14.41% |
| 2012 | 132886 | Metric tons | -22.09% |
| 2013 | 127658 | Metric tons | -3.93% |
