Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 1061.20397949219 | Thousand metric tons of contained nitrogen | NA |
| 2004 | 1101.42602539063 | Thousand metric tons of contained nitrogen | 3.79 % |
| 2005 | 1083.15002441406 | Thousand metric tons of contained nitrogen | -1.66 % |
| 2006 | 1091 | Thousand metric tons of contained nitrogen | 0.72 % |
| 2007 | 1114 | Thousand metric tons of contained nitrogen | 2.11 % |
| 2008 | 1110 | Thousand metric tons of contained nitrogen | -0.36 % |
| 2009 | 1120 | Thousand metric tons of contained nitrogen | 0.90 % |
