Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 2703.32788085938 | Thousand metric tons | NA |
| 2004 | 2516.36206054688 | Thousand metric tons | -6.92% |
| 2005 | 2480.9990234375 | Thousand metric tons | -1.41% |
| 2006 | 2283.8310546875 | Thousand metric tons | -7.95% |
| 2007 | 2553.88403320313 | Thousand metric tons | 11.82% |
| 2008 | 2658.26708984375 | Thousand metric tons | 4.09% |
| 2009 | 1727.16198730469 | Thousand metric tons | -35.03% |
| 2010 | 1725.72998046875 | Thousand metric tons | -0.08% |
| 2011 | 1986.02600097656 | Thousand metric tons | 15.08% |
| 2012 | 2070.31396484375 | Thousand metric tons | 4.24% |
| 2013 | 1946.03503417969 | Thousand metric tons | -6.00% |
