Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 272.368988037109 | Thousand metric tons | NA |
| 2004 | 272.048004150391 | Thousand metric tons | -0.12% |
| 2005 | 270.713989257813 | Thousand metric tons | -0.49% |
| 2006 | 272.941986083984 | Thousand metric tons | 0.82% |
| 2007 | 270.700012207031 | Thousand metric tons | -0.82% |
| 2008 | 393.899993896484 | Thousand metric tons | 45.51% |
| 2009 | 412.593994140625 | Thousand metric tons | 4.75% |
| 2010 | 417.088012695313 | Thousand metric tons | 1.09% |
| 2011 | 416.177001953125 | Thousand metric tons | -0.22% |
| 2012 | 413.394989013672 | Thousand metric tons | -0.67% |
| 2013 | 425 | Thousand metric tons | 2.81% |
