Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 1900 | Thousand metric tons | NA |
| 2003 | 2119 | Thousand metric tons | 11.53% |
| 2004 | 1882 | Thousand metric tons | -11.18% |
| 2005 | 2047.94995117188 | Thousand metric tons | 8.82% |
| 2006 | 2092.99609375 | Thousand metric tons | 2.20% |
| 2007 | 2152.82495117188 | Thousand metric tons | 2.86% |
| 2008 | 2032.67102050781 | Thousand metric tons | -5.58% |
| 2009 | 2002.13098144531 | Thousand metric tons | -1.50% |
| 2010 | 2068.85302734375 | Thousand metric tons | 3.33% |
| 2011 | 2206.90991210938 | Thousand metric tons | 6.67% |
| 2012 | 2200 | Thousand metric tons | -0.31% |
