Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 165.289993286133 | Thousand metric tons | NA |
| 2004 | 175 | Thousand metric tons | 5.87% |
| 2005 | 162.483001708984 | Thousand metric tons | -7.15% |
| 2006 | 158.289001464844 | Thousand metric tons | -2.58% |
| 2007 | 160.460998535156 | Thousand metric tons | 1.37% |
| 2008 | 162.994995117188 | Thousand metric tons | 1.58% |
| 2009 | 149.60400390625 | Thousand metric tons | -8.22% |
| 2010 | 162.996994018555 | Thousand metric tons | 8.95% |
| 2011 | 162.839996337891 | Thousand metric tons | -0.10% |
| 2012 | 180.671005249023 | Thousand metric tons | 10.95% |
| 2013 | 160 | Thousand metric tons | -11.44% |
