Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 288 | Thousand metric tons of contained nitrogen | NA |
| 2004 | 275.222991943359 | Thousand metric tons of contained nitrogen | -4.44% |
| 2005 | 236.039993286133 | Thousand metric tons of contained nitrogen | -14.24% |
| 2006 | 241.382995605469 | Thousand metric tons of contained nitrogen | 2.26% |
| 2007 | 260 | Thousand metric tons of contained nitrogen | 7.71% |
| 2008 | 260 | Thousand metric tons of contained nitrogen | 0.00% |
| 2009 | 260 | Thousand metric tons of contained nitrogen | 0.00% |
| 2010 | 493 | Thousand metric tons of contained nitrogen | 89.62% |
| 2011 | 486.688995361328 | Thousand metric tons of contained nitrogen | -1.28% |
| 2012 | 485.518005371094 | Thousand metric tons of contained nitrogen | -0.24% |
