National Trends in Nitrogen_Dioxide Concentrations in 1980 - 2017

Year	Mean	Number of Trend Sites	10th Percentile	90th Percentile
1980	111.434782608695	23	68	190
1981	107.086956521739	23	65	190
1982	107.521739130434	23	68	190
1983	98.2608695652174	23	60	160
1984	93.6594202898551	23	60	140
1985	95.7536231884057	23	60	170
1986	97.4347826086956	23	60	180
1987	96.4347826086956	23	64	160
1988	100.934782608695	23	64	175
1989	99	23	58	160
1990	92.8695652173913	23	55	160
1991	94.9565217391304	23	57	170
1992	81.5652173913043	23	51	130
1993	79.3043478260869	23	53	140
1994	82.3478260869565	23	53	129
1995	82.4347826086956	23	52	159
1996	74.3478260869565	23	50	130.5
1997	70.7391304347826	23	50	106
1998	68.0869565217391	23	45	115
1999	72.4565217391304	23	48	116
2000	65.4782608695652	23	45	114
2001	65.6739130434782	23	45	104
2002	62.7826086956521	23	45	96
2003	62.4130434782608	23	43	100
2004	56.8768115942029	23	41	89
2005	56.5579710144927	23	42	77
2006	55.7826086956521	23	41	84
2007	54	23	41	78.5
2008	52.9782608695652	23	37	81.5
2009	48.7695652173913	23	35	70.8
2010	48.0347826086956	23	38	61.6
2011	48.7195652173913	23	37.9	66.7
2012	45.0565217391304	23	35.7	60.6
2013	45.4702898550724	23	34	58.45
2014	47.7905797101449	23	38.25	61
2015	45.0478260869565	23	33	60.3
2016	43.6782608695652	23	32.5	58.3
2017	44.1086956521739	23	31.9	57.7