Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 62005 | Metric tons, gross weight | NA |
| 2003 | 98235 | Metric tons, gross weight | 58.43% |
| 2004 | 129500 | Metric tons, gross weight | 31.83% |
| 2005 | 148432 | Metric tons, gross weight | 14.62% |
| 2006 | 199000 | Metric tons, gross weight | 34.07% |
| 2007 | 323100 | Metric tons, gross weight | 62.36% |
| 2008 | 104000 | Metric tons, gross weight | -67.81% |
| 2009 | 133000 | Metric tons, gross weight | 27.88% |
| 2010 | 252000 | Metric tons, gross weight | 89.47% |
| 2011 | 250000 | Metric tons, gross weight | -0.79% |
| 2012 | 260000 | Metric tons, gross weight | 4.00% |
