Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 36484.015625 | Thousand metric tons | NA |
| 2003 | 38085.85546875 | Thousand metric tons | 4.39% |
| 2004 | 39322 | Thousand metric tons | 3.25% |
| 2005 | 39542.0703125 | Thousand metric tons | 0.56% |
| 2006 | 41326.03515625 | Thousand metric tons | 4.51% |
| 2007 | 42083 | Thousand metric tons | 1.83% |
| 2008 | 48982.53515625 | Thousand metric tons | 16.40% |
| 2009 | 55313.0546875 | Thousand metric tons | 12.92% |
| 2010 | 58709.328125 | Thousand metric tons | 6.14% |
| 2011 | 58056.8984375 | Thousand metric tons | -1.11% |
| 2012 | 63000 | Thousand metric tons | 8.51% |
