Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 2791.9150390625 | Thousand metric tons | NA |
| 2004 | 2592.15991210938 | Thousand metric tons | -7.15% |
| 2005 | 2894.2041015625 | Thousand metric tons | 11.65% |
| 2006 | 3051.1279296875 | Thousand metric tons | 5.42% |
| 2007 | 3082.625 | Thousand metric tons | 1.03% |
| 2008 | 3120.14794921875 | Thousand metric tons | 1.22% |
| 2009 | 3030.26904296875 | Thousand metric tons | -2.88% |
| 2010 | 2963.2099609375 | Thousand metric tons | -2.21% |
| 2011 | 2987.96411132813 | Thousand metric tons | 0.84% |
| 2012 | 2780.55590820313 | Thousand metric tons | -6.94% |
| 2013 | 2967.36401367188 | Thousand metric tons | 6.72% |
