Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 116.744003295898 | Thousand metric tons | NA |
| 2004 | 115.080001831055 | Thousand metric tons | -1.43% |
| 2005 | 116.995002746582 | Thousand metric tons | 1.66% |
| 2006 | 121.762001037598 | Thousand metric tons | 4.07% |
| 2007 | 124.059997558594 | Thousand metric tons | 1.89% |
| 2008 | 107.457000732422 | Thousand metric tons | -13.38% |
| 2009 | 63.9599990844727 | Thousand metric tons | -40.48% |
| 2010 | 82.0429992675781 | Thousand metric tons | 28.27% |
| 2011 | 92.8379974365234 | Thousand metric tons | 13.16% |
| 2012 | 90 | Thousand metric tons | -3.06% |
| 2013 | 80 | Thousand metric tons | -11.11% |
