Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2002 | 728 | Thousand metric tons | NA |
| 2003 | 714 | Thousand metric tons | -1.92% |
| 2004 | 797 | Thousand metric tons | 11.62% |
| 2005 | 760 | Thousand metric tons | -4.64% |
| 2006 | 800 | Thousand metric tons | 5.26% |
| 2007 | 780 | Thousand metric tons | -2.50% |
| 2008 | 1091 | Thousand metric tons | 39.87% |
| 2009 | 1000 | Thousand metric tons | -8.34% |
| 2010 | 1078 | Thousand metric tons | 7.80% |
| 2011 | 1319 | Thousand metric tons | 22.36% |
| 2012 | 1217 | Thousand metric tons | -7.73% |
