Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 81100 | Metric tons | NA |
| 2003 | 78600 | Metric tons | -3.08% |
| 2004 | 99200 | Metric tons | 26.21% |
| 2005 | 78100 | Metric tons | -21.27% |
| 2006 | 110000 | Metric tons | 40.85% |
| 2007 | 96600 | Metric tons | -12.18% |
| 2008 | 84000 | Metric tons | -13.04% |
| 2009 | 51100 | Metric tons | -39.17% |
| 2010 | 56100 | Metric tons | 9.78% |
| 2011 | 52000 | Metric tons | -7.31% |
| 2012 | 47500 | Metric tons | -8.65% |
| 2013 | 48100 | Metric tons | 1.26% |
