Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 6435746 | Metric tons, gross weight | NA |
| 2003 | 7405391 | Metric tons, gross weight | 15.07% |
| 2004 | 7677000 | Metric tons, gross weight | 3.67% |
| 2005 | 7552000 | Metric tons, gross weight | -1.63% |
| 2006 | 7418326 | Metric tons, gross weight | -1.77% |
| 2007 | 9646958 | Metric tons, gross weight | 30.04% |
| 2008 | 9682640 | Metric tons, gross weight | 0.37% |
| 2009 | 7560938 | Metric tons, gross weight | -21.91% |
| 2010 | 10871095 | Metric tons, gross weight | 43.78% |
| 2011 | 10721360 | Metric tons, gross weight | -1.38% |
| 2012 | 11000000 | Metric tons, gross weight | 2.60% |
