Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 32577 | Thousand metric tons | NA |
| 2003 | 35077 | Thousand metric tons | 7.67% |
| 2004 | 38795.796875 | Thousand metric tons | 10.60% |
| 2005 | 42786.8359375 | Thousand metric tons | 10.29% |
| 2006 | 47499.16015625 | Thousand metric tons | 11.01% |
| 2007 | 49552.55078125 | Thousand metric tons | 4.32% |
| 2008 | 51432 | Thousand metric tons | 3.79% |
| 2009 | 53973 | Thousand metric tons | 4.94% |
| 2010 | 62737 | Thousand metric tons | 16.24% |
| 2011 | 63405 | Thousand metric tons | 1.06% |
| 2012 | 63879 | Thousand metric tons | 0.75% |
