| States | Arizona | Arkansas | California | Colorado | Idaho | Kansas | Missouri | Nevada | Montana | Oregon | Texas |
| 2000 | 3 | 0 | 0.4 | 2.4 | 0.1 | 0 | 0.1 | 0.1 | 0.2 | 0.1 | 0 |
| 2001 | 3 | 0 | 0.4 | 2.5 | 0 | 0 | 0.1 | 0.2 | 0.1 | 0.1 | 0 |
| 2002 | 1.5 | 0 | 0.4 | 2 | 0.2 | 0 | 0 | 0.1 | 0.1 | 0.3 | 0.1 |
| 2003 | 0 | 0 | 0.4 | 0.4 | 0 | 0 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 |
| 2004 | 0 | 0 | 0.4 | 0.2 | 0.1 | 0 | 0.1 | 0.1 | 0.1 | 0.4 | 0 |
| 2005 | 0 | 0.1 | 0.3 | 0.5 | 0.1 | 0 | 0.1 | 0.1 | 0.2 | 0.1 | 0 |
| 2006 | 0 | 0 | 0.4 | 1 | 0.1 | 0 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 |
| 2007 | 0.1 | 0 | 0.5 | 0.6 | 0.1 | 0 | 0.1 | 0.1 | 0.1 | 0.5 | 0.1 |
| 2008 | 0.1 | 0.2 | 0.6 | 0.6 | 0.1 | 0 | 0.2 | 0.2 | 0.1 | 0.1 | 0.4 |
| 2009 | 0.1 | 0.1 | 0.6 | 0.6 | 0.1 | 0 | 0.1 | 0.1 | 0.1 | 0.2 | 0.3 |
| 2010 | 0.3 | 2.6 | 2 | 1 | 0.3 | 0 | 0.5 | 0.2 | 1.5 | 0.4 | 7 |
| 2011 | 0.1 | 9 | 1 | 1 | 0.1 | 0 | 1 | 0.2 | 0.2 | 0.3 | 2 |
| 2012 | 0.3 | 0.2 | 1 | 0.4 | 0.1 | 0 | 0.5 | 0.1 | 0.3 | 0.3 | 1 |
| 2013 | 0.2 | 0.4 | 0.7 | 0.7 | 0.2 | 0 | 1 | 0.2 | 0.2 | 0.7 | 1.5 |
| 2014 | 2 | 1.6 | 3.5 | 0.8 | 4 | 3 | 3.2 | 5 | 3 | 4.5 | 1 |
| 2015 | 1.7 | 1 | 4 | 0.6 | 5 | 4 | 5 | 6 | 4 | 4.4 | 2 |
| 2016 | 2 | 0.6 | 4.5 | 0.7 | 4.5 | 9 | 3 | 4 | 5 | 2.8 | 0.3 |