Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 815 | Thousand metric tons of contained nitrogen | NA |
| 2004 | 875.299987792969 | Thousand metric tons of contained nitrogen | 7.40% |
| 2005 | 880 | Thousand metric tons of contained nitrogen | 0.54% |
| 2006 | 940 | Thousand metric tons of contained nitrogen | 6.82% |
| 2007 | 1000 | Thousand metric tons of contained nitrogen | 6.38% |
| 2008 | 1000 | Thousand metric tons of contained nitrogen | 0.00% |
| 2009 | 1000 | Thousand metric tons of contained nitrogen | 0.00% |
| 2010 | 1344.02905273438 | Thousand metric tons of contained nitrogen | 34.40% |
| 2011 | 1294.30004882813 | Thousand metric tons of contained nitrogen | -3.70% |
| 2012 | 1300 | Thousand metric tons of contained nitrogen | 0.44% |
