Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 1739.98803710938 | Thousand metric tons | NA |
| 2003 | 1946.90002441406 | Thousand metric tons | 11.89% |
| 2004 | 2329.4169921875 | Thousand metric tons | 19.65% |
| 2005 | 2270 | Thousand metric tons | -2.55% |
| 2006 | 2146 | Thousand metric tons | -5.46% |
| 2007 | 1723 | Thousand metric tons | -19.71% |
| 2008 | 2020 | Thousand metric tons | 17.24% |
| 2009 | 2092 | Thousand metric tons | 3.56% |
| 2010 | 2439 | Thousand metric tons | 16.59% |
| 2011 | 2357 | Thousand metric tons | -3.36% |
| 2012 | 2400 | Thousand metric tons | 1.82% |
