National Trends in Nitrogen_Dioxide Concentrations in 1990 - 2012
Year Mean Number of Trend Sites 10th Percentile 90th Percentile
1990 79.3092783505154 97 46 130
1991 78.8384879725086 97 44.5 130
1992 72.3419243986254 97 39 120
1993 70.5824742268041 97 44 110
1994 71.9845360824742 97 41 116
1995 70.9536082474226 97 35 111
1996 66.0051546391752 97 39 106
1997 63.520618556701 97 37 98
1998 61.9776632302405 97 35 97
1999 66.1288659793814 97 35 99
2000 61.3745704467354 97 35 92
2001 59.5756013745704 97 33 86
2002 58.5463917525773 97 32.5 93
2003 57.5360824742268 97 35 83
2004 52.8780068728522 97 29 80
2005 52.1237113402061 97 29 75
2006 51.127147766323 97 29 74
2007 49.9931271477663 97 29 71
2008 49.8213058419244 97 29 71
2009 45.0541237113402 97 25 63.5
2010 45.194501718213 97 23 64
2011 44.2884879725085 97 21 64
2012 42.4762886597938 97 21 61.2