Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 58900 | Thousand metric tons | NA |
| 2003 | 62497.6015625 | Thousand metric tons | 6.11% |
| 2004 | 65550 | Thousand metric tons | 4.88% |
| 2005 | 68569.6015625 | Thousand metric tons | 4.61% |
| 2006 | 74000 | Thousand metric tons | 7.92% |
| 2007 | 77900 | Thousand metric tons | 5.27% |
| 2008 | 72688 | Thousand metric tons | -6.69% |
| 2009 | 66476 | Thousand metric tons | -8.55% |
| 2010 | 78170.703125 | Thousand metric tons | 17.59% |
| 2011 | 80580.796875 | Thousand metric tons | 3.08% |
| 2012 | 81966.3984375 | Thousand metric tons | 1.72% |
