Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 37700 | Thousand metric tons | NA |
| 2003 | 41000 | Thousand metric tons | 8.75% |
| 2004 | 45700 | Thousand metric tons | 11.46% |
| 2005 | 48500 | Thousand metric tons | 6.13% |
| 2006 | 54700 | Thousand metric tons | 12.78% |
| 2007 | 59900 | Thousand metric tons | 9.51% |
| 2008 | 53548 | Thousand metric tons | -10.60% |
| 2009 | 44266 | Thousand metric tons | -17.33% |
| 2010 | 50400 | Thousand metric tons | 13.86% |
| 2011 | 56200 | Thousand metric tons | 11.51% |
| 2012 | 61700 | Thousand metric tons | 9.79% |
