Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 27500 | Metric tons | NA |
| 2003 | 30300 | Metric tons | 10.18% |
| 2004 | 31800 | Metric tons | 4.95% |
| 2005 | 44200 | Metric tons | 38.99% |
| 2006 | 83000 | Metric tons | 87.78% |
| 2007 | 108000 | Metric tons | 30.12% |
| 2008 | 185000 | Metric tons | 71.30% |
| 2009 | 178000 | Metric tons | -3.78% |
| 2010 | 160000 | Metric tons | -10.11% |
| 2011 | 174000 | Metric tons | 8.75% |
| 2012 | 190000 | Metric tons | 9.20% |
