Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 55.2999992370605 | Thousand metric tons of contained nitrogen | NA |
| 2004 | 47.5 | Thousand metric tons of contained nitrogen | -14.10% |
| 2005 | 30 | Thousand metric tons of contained nitrogen | -36.84% |
| 2006 | 10 | Thousand metric tons of contained nitrogen | -66.67% |
| 2007 | 35 | Thousand metric tons of contained nitrogen | 250.00% |
| 2008 | 20 | Thousand metric tons of contained nitrogen | -42.86% |
| 2009 | 14 | Thousand metric tons of contained nitrogen | -30.00% |
| 2010 | 29 | Thousand metric tons of contained nitrogen | 107.14% |
| 2011 | 26 | Thousand metric tons of contained nitrogen | -10.34% |
| 2012 | 25 | Thousand metric tons of contained nitrogen | -3.85% |
