Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 127.599998474121 | Thousand metric tons of contained nitrogen | NA |
| 2004 | 124.300003051758 | Thousand metric tons of contained nitrogen | -2.59% |
| 2005 | 120 | Thousand metric tons of contained nitrogen | -3.46% |
| 2006 | 120 | Thousand metric tons of contained nitrogen | 0.00% |
| 2007 | 125 | Thousand metric tons of contained nitrogen | 4.17% |
| 2008 | 125 | Thousand metric tons of contained nitrogen | 0.00% |
| 2009 | 125 | Thousand metric tons of contained nitrogen | 0.00% |
| 2010 | 120 | Thousand metric tons of contained nitrogen | -4.00% |
| 2011 | 120 | Thousand metric tons of contained nitrogen | 0.00% |
| 2012 | 120 | Thousand metric tons of contained nitrogen | 0.00% |
