Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 77.0999984741211 | Thousand metric tons of contained nitrogen | NA |
| 2004 | 60.5999984741211 | Thousand metric tons of contained nitrogen | -21.40 % |
| 2005 | 63 | Thousand metric tons of contained nitrogen | 3.96 % |
| 2006 | 62 | Thousand metric tons of contained nitrogen | -1.59 % |
| 2007 | 62 | Thousand metric tons of contained nitrogen | 0.00 % |
| 2008 | 62 | Thousand metric tons of contained nitrogen | 0.00 % |
| 2009 | 62 | Thousand metric tons of contained nitrogen | 0.00 % |
