Year,Jan.,Feb.,Mar.,Apr.,May.,Jun.,Jul.,Aug.,Sep.,Oct.,Nov.,Dec.,24-Hour Annual Avg., 1990,8475,9200,10698,11058,11560,12767,12902,13493,11703,10866,10554,8874,11022, 1991,8741,11714,13588,10993,11485,13152,13215,13997,12139,11737,10736,10454,11831, 1992,9336,10565,11545,11931,12615,14050,14103,14500,13056,12619,11313,10342,12202, 1993,9080,10354,11671,12905,14522,14076,15114,15294,13494,12836,12011,11393,12744, 1994,10394,10925,13116,13251,13576,14645,15290,16478,14153,13878,12157,11590,13304, 1995,10973,11825,13207,13390,13449,,16969,16603,14836,13860,13240,11932,, 1996,10469,12331,14284,14590,15197,16141,16652,17132,15238,14514,13815,12650,14418, 1997,11847,13182,14806,14668,14819,16458,16838,,15823,14818,14539,13918,, 1998,12547,13896,15214,15807,16308,17830,18053,18698,16741,16027,15574,14375,15923, 1999,13319,14139,16219,16202,16295,17380,18349,19603,17150,16648,16186,14977,16372, 2000,13242,14923,16600,16831,17393,18584,19093,19912,17528,16695,15961,15085,16821, 2001,13822,14845,16988,16287,17946,19099,19356,19864,18228,17247,16727,15255,17139, 2002,14528,,,17156,19046,20059,,20867,18545,18049,17249,16713,, 2003,15476,16138,16709,18115,18804,,20514,21493,19008,18275,17099,16213,, 2004,13460,16416,18007,18483,18606,19400,20374,20918,,,18032,16535,, 2005,14746,16424,18376,18305,18634,20306,20883,20675,18691,17821,17793,16013,18222, 2006,15055,16566,18433,19095,19240,20004,20498,20894,19286,18413,18016,16600,18508, 2007,15273,,18529,19455,19708,20473,20812,21490,19277,18680,18365,16334,, 2008,13797,,18016,17979,18682,19235,19587,19972,17941,17592,17397,15279,, 2009,13602,14292,17438,18598,19328,19705,20577,20597,19270,18049,17598,15322,, 2010,14966,16530,18261,18448,,20510,21066,20942,19085,18125,16731,17207,, 2011,14957,16353,18026,18155,18466,19766,20364,19813,18644,17575,17362,16577,18005, 2012,14553,16361,17867,18379,18876,20290,20620,21182,19142,18754,18070,16703,18400, 2013,14587,16195,18499,18558,19521,20525,21114,21583,19392,19056,18112,16975,18676, 2014,15841,16640,19574,19731,20447,21933,22220,22479,20521,20077,18761,18147,19698, 2015,16812,18791,20541,21035,22029,23858,24114,23808,22235,21433,19753,18372,21065, 2016,17157,19482,21090,21630,23301,24946,25466,25241,23170,22006,21613,18303,21951, 2017,15477,18697,22345,23258,24153,25394,25725,24466,21785,,21770,19697,22045, 2018,18535,19701,23351,23094,22734,24642,25826,25581,23825,22535,22214,19980,22668, 2019,18926,18377,22152,23047,24515,26202,26724,26213,24581,23873,22459,20966,23170, 2020,19022,20587,20355,15952,20753,24348,25211,25660,24943,23873,21268,20372,21862, 2021,19890,20019,24334,25159,26274,28404,28821,28075,25951,25134,24894,21779,24894, 2022,19952,22361,25035,25301,26518,27810,27202,27367,26000,25572,23777,21001,24823, 2023,20318,21500,24016,25379,27229,28672,28595,28126,26357,25982,24465,21978,25218, 2024,18967,22583, , , , , , , , , , , ,