Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 67700 | Metric tons | NA |
| 2004 | 85400 | Metric tons | 26.14% |
| 2005 | 85400 | Metric tons | 0.00% |
| 2006 | 80400 | Metric tons | -5.85% |
| 2007 | 81000 | Metric tons | 0.75% |
| 2008 | 80000 | Metric tons | -1.23% |
| 2009 | 84097 | Metric tons | 5.12% |
| 2010 | 110700 | Metric tons | 31.63% |
| 2011 | 97071 | Metric tons | -12.31% |
| 2012 | 91200 | Metric tons | -6.05% |
| 2013 | 100000 | Metric tons | 9.65% |
