Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 235 | Thousand metric tons of contained nitrogen | NA |
| 2004 | 233.399993896484 | Thousand metric tons of contained nitrogen | -0.68 % |
| 2005 | 250 | Thousand metric tons of contained nitrogen | 7.11 % |
| 2006 | 250 | Thousand metric tons of contained nitrogen | 0.00 % |
| 2007 | 225 | Thousand metric tons of contained nitrogen | -10.00 % |
| 2008 | 200 | Thousand metric tons of contained nitrogen | -11.11 % |
| 2009 | 200 | Thousand metric tons of contained nitrogen | 0.00 % |
