Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 231117 | Metric tons | NA |
| 2004 | 252067 | Metric tons | 9.06% |
| 2005 | 236047 | Metric tons | -6.36% |
| 2006 | 227304 | Metric tons | -3.70% |
| 2007 | 254204 | Metric tons | 11.83% |
| 2008 | 287673 | Metric tons | 13.17% |
| 2009 | 288452 | Metric tons | 0.27% |
| 2010 | 302257 | Metric tons | 4.79% |
| 2011 | 306321 | Metric tons | 1.34% |
| 2012 | 304569 | Metric tons | -0.57% |
| 2013 | 307000 | Metric tons | 0.80% |
