Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 204027 | Metric tons | NA |
| 2003 | 199020 | Metric tons | -2.45% |
| 2004 | 177143 | Metric tons | -10.99% |
| 2005 | 187317 | Metric tons | 5.74% |
| 2006 | 180144 | Metric tons | -3.83% |
| 2007 | 180200 | Metric tons | 0.03% |
| 2008 | 156893 | Metric tons | -12.93% |
| 2009 | 143084 | Metric tons | -8.80% |
| 2010 | 140001 | Metric tons | -2.15% |
| 2011 | 116698 | Metric tons | -16.64% |
| 2012 | 136000 | Metric tons | 16.54% |
