Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 1399 | Thousand metric tons | NA |
| 2004 | 1587.99194335938 | Thousand metric tons | 13.51% |
| 2005 | 1953.22705078125 | Thousand metric tons | 23.00% |
| 2006 | 1948.26794433594 | Thousand metric tons | -0.25% |
| 2007 | 2127.81201171875 | Thousand metric tons | 9.22% |
| 2008 | 1500 | Thousand metric tons | -29.51% |
| 2009 | 1740 | Thousand metric tons | 16.00% |
| 2010 | 2220 | Thousand metric tons | 27.59% |
| 2011 | 2130 | Thousand metric tons | -4.05% |
| 2012 | 1632 | Thousand metric tons | -23.38% |
| 2013 | 1572 | Thousand metric tons | -3.68% |
