Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 118.900001525879 | Thousand metric tons of contained nitrogen | NA |
| 2004 | 163.399993896484 | Thousand metric tons of contained nitrogen | 37.43% |
| 2005 | 165 | Thousand metric tons of contained nitrogen | 0.98% |
| 2006 | 90 | Thousand metric tons of contained nitrogen | -45.45% |
| 2007 | 100 | Thousand metric tons of contained nitrogen | 11.11% |
