Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 15423.099609375 | Thousand metric tons | NA |
| 2003 | 19280.900390625 | Thousand metric tons | 25.01 % |
| 2004 | 18725.69921875 | Thousand metric tons | -2.88 % |
| 2005 | 19471.099609375 | Thousand metric tons | 3.98 % |
| 2006 | 22262.599609375 | Thousand metric tons | 14.34 % |
| 2007 | 23834.099609375 | Thousand metric tons | 7.06 % |
| 2008 | 21486 | Thousand metric tons | -9.85 % |
| 2009 | 22281.30078125 | Thousand metric tons | 3.70 % |
| 2010 | 24229.099609375 | Thousand metric tons | 8.74 % |
| 2011 | 24812.80078125 | Thousand metric tons | 2.41 % |
| 2012 | 25997.80078125 | Thousand metric tons | 4.78 % |
