Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 70739 | Metric tons | NA |
| 2004 | 76332 | Metric tons | 7.91% |
| 2005 | 77494 | Metric tons | 1.52% |
| 2006 | 76194 | Metric tons | -1.68% |
| 2007 | 77163 | Metric tons | 1.27% |
| 2008 | 76200 | Metric tons | -1.25% |
| 2009 | 59425 | Metric tons | -22.01% |
| 2010 | 92364 | Metric tons | 55.43% |
| 2011 | 105188 | Metric tons | 13.88% |
| 2012 | 88100 | Metric tons | -16.25% |
| 2013 | 95000 | Metric tons | 7.83% |
