Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 635.481018066406 | Thousand metric tons | NA |
| 2004 | 959.018981933594 | Thousand metric tons | 50.91% |
| 2005 | 1115.19494628906 | Thousand metric tons | 16.28% |
| 2006 | 1529.17700195313 | Thousand metric tons | 37.12% |
| 2007 | 1485 | Thousand metric tons | -2.89% |
| 2008 | 1582 | Thousand metric tons | 6.53% |
| 2009 | 1006 | Thousand metric tons | -36.41% |
| 2010 | 1265 | Thousand metric tons | 25.75% |
| 2011 | 1226 | Thousand metric tons | -3.08% |
| 2012 | 312 | Thousand metric tons | -74.55% |
