National Trends in Nitrogen_Dioxide Concentrations in 2000 - 2014

Year	Mean	Number of Trend Sites	10th Percentile	90th Percentile
2000	57.5311377245509	167	35	81
2001	56.6580838323353	167	34	77
2002	55.1077844311377	167	32	81
2003	53.915369261477	167	32	79
2004	50.6644710578842	167	29	73
2005	50.3616766467066	167	29	73
2006	49.3301397205588	167	28	71
2007	48.1289421157684	167	27	65
2008	47.4097804391217	167	28	66
2009	43.3809381237525	167	24	60
2010	44.0779441117764	167	25	59.6
2011	43.2807385229541	167	24	60.1
2012	41.2187624750499	167	23	59.5
2013	40.9255489021956	167	21	58.45
2014	40.902994011976	167	21.8	57.9