Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 3900 | Thousand metric tons of contained nitrogen | NA |
| 2004 | 3900 | Thousand metric tons of contained nitrogen | 0.00% |
| 2005 | 4300 | Thousand metric tons of contained nitrogen | 10.26% |
| 2006 | 4200 | Thousand metric tons of contained nitrogen | -2.33% |
| 2007 | 4200 | Thousand metric tons of contained nitrogen | 0.00% |
| 2008 | 4000 | Thousand metric tons of contained nitrogen | -4.76% |
| 2009 | 2500 | Thousand metric tons of contained nitrogen | -37.50% |
| 2010 | 3400 | Thousand metric tons of contained nitrogen | 36.00% |
| 2011 | 4300 | Thousand metric tons of contained nitrogen | 26.47% |
| 2012 | 4160 | Thousand metric tons of contained nitrogen | -3.26% |
