National Trends in Carbon_Monoxide Concentrations in 1980 - 2017
| Year |
Mean |
Number of Trend Sites |
10th Percentile |
90th Percentile |
| 1980 |
8.81764705882353 |
51 |
4.6 |
13 |
| 1981 |
8.7578431372549 |
51 |
4.4 |
12.9 |
| 1982 |
8.18366013071895 |
51 |
4.8 |
13.2 |
| 1983 |
8.54183006535947 |
51 |
4 |
13.2 |
| 1984 |
8.04509803921568 |
51 |
4.6 |
13 |
| 1985 |
7.30882352941176 |
51 |
3.9 |
11 |
| 1986 |
7.57254901960784 |
51 |
3.9 |
11.2 |
| 1987 |
6.8843137254902 |
51 |
3.9 |
9.5 |
| 1988 |
6.80980392156863 |
51 |
4.2 |
10.3 |
| 1989 |
6.69607843137255 |
51 |
3.7 |
10.3 |
| 1990 |
6.24901960784313 |
51 |
3.4 |
9.5 |
| 1991 |
6.11176470588235 |
51 |
3.3 |
8.9 |
| 1992 |
5.58823529411764 |
51 |
3.2 |
8 |
| 1993 |
5.30980392156862 |
51 |
3.1 |
7.4 |
| 1994 |
5.51176470588235 |
51 |
3.2 |
8.2 |
| 1995 |
4.87843137254901 |
51 |
2.7 |
7.7 |
| 1996 |
4.45294117647059 |
51 |
2.7 |
6.7 |
| 1997 |
4.08627450980392 |
51 |
2.4 |
5.9 |
| 1998 |
3.99411764705882 |
51 |
2.3 |
5.9 |
| 1999 |
4 |
51 |
2.2 |
6 |
| 2000 |
3.54117647058823 |
51 |
2 |
5.2 |
| 2001 |
3.23725490196078 |
51 |
1.8 |
4.8 |
| 2002 |
2.88039215686274 |
51 |
1.8 |
4.1 |
| 2003 |
2.74509803921568 |
51 |
1.8 |
3.8 |
| 2004 |
2.61176470588235 |
51 |
1.6 |
3.8 |
| 2005 |
2.24019607843137 |
51 |
1.4 |
3.2 |
| 2006 |
2.18039215686274 |
51 |
1.3 |
3.1 |
| 2007 |
1.95490196078431 |
51 |
1.2 |
2.8 |
| 2008 |
1.72156862745098 |
51 |
1.1 |
2.5 |
| 2009 |
1.70392156862745 |
51 |
0.8 |
2.5 |
| 2010 |
1.6 |
51 |
0.9 |
2.4 |
| 2011 |
1.61372549019607 |
51 |
1 |
2.2 |
| 2012 |
1.54215686274509 |
51 |
1 |
2.1 |
| 2013 |
1.47058823529411 |
51 |
0.8 |
2.2 |
| 2014 |
1.41372549019607 |
51 |
0.9 |
2.4 |
| 2015 |
1.4313725490196 |
51 |
0.9 |
1.9 |
| 2016 |
1.38039215686274 |
51 |
0.9 |
1.9 |
| 2017 |
1.39607843137254 |
51 |
0.9 |
1.9 |