Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 1327 | Thousand metric tons | NA |
| 2003 | 1346 | Thousand metric tons | 1.43% |
| 2004 | 1401.30004882813 | Thousand metric tons | 4.11% |
| 2005 | 1566.90002441406 | Thousand metric tons | 11.82% |
| 2006 | 1704.69995117188 | Thousand metric tons | 8.79% |
| 2007 | 1805.30004882813 | Thousand metric tons | 5.90% |
| 2008 | 1707 | Thousand metric tons | -5.45% |
| 2009 | 1626 | Thousand metric tons | -4.75% |
| 2010 | 1631 | Thousand metric tons | 0.31% |
| 2011 | 1736 | Thousand metric tons | 6.44% |
| 2012 | 1833 | Thousand metric tons | 5.59% |
