Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 77227 | Metric tons | NA |
| 2003 | 77581 | Metric tons | 0.46% |
| 2004 | 95743 | Metric tons | 23.41% |
| 2005 | 89541 | Metric tons | -6.48% |
| 2006 | 78600 | Metric tons | -12.22% |
| 2007 | 90200 | Metric tons | 14.76% |
| 2008 | 89504 | Metric tons | -0.77% |
| 2009 | 86500 | Metric tons | -3.36% |
| 2010 | 74426 | Metric tons | -13.96% |
| 2011 | 79686 | Metric tons | 7.07% |
| 2012 | 82500 | Metric tons | 3.53% |
