Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 107.800003051758 | Thousand metric tons of contained nitrogen | NA |
| 2004 | 98.1999969482422 | Thousand metric tons of contained nitrogen | -8.91% |
| 2005 | 100 | Thousand metric tons of contained nitrogen | 1.83% |
| 2006 | 100 | Thousand metric tons of contained nitrogen | 0.00% |
| 2007 | 100 | Thousand metric tons of contained nitrogen | 0.00% |
