Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 112.502998352051 | Thousand metric tons | NA |
| 2004 | 121.295997619629 | Thousand metric tons | 7.82 % |
| 2005 | 131.231994628906 | Thousand metric tons | 8.19 % |
| 2006 | 136.190002441406 | Thousand metric tons | 3.78 % |
| 2007 | 121.75 | Thousand metric tons | -10.60 % |
| 2008 | 123 | Thousand metric tons | 1.03 % |
| 2009 | 96 | Thousand metric tons | -21.95 % |
