YEAR Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual 24-hr Avg. 1990 13694 14313 15202 15722 16182 16629 15352 15884 15359 15447 14732 13185 15144 1991 13466 15091 16600 18484 17948 17164 16340 16294 15841 15549 14482 14818 16009 1992 15129 15197 15708 16512 17163 16676 15966 15680 15714 15496 14411 14699 15740 1993 12797 14386 15052 16049 16428 16504 15234 15433 15703 15613 15257 14919 15282 1994 14213 15049 16248 17100 17421 17337 16143 16440 16236 16147 15779 14064 16016 1995 14938 15373 1996 14476 15304 15994 16713 16803 16738 15903 16529 15831 15451 15572 15114 15869 1997 14301 15668 16043 16648 17027 16735 16044 15975 15856 15487 14811 14753 15779 1998 14001 15199 16189 16390 16680 16610 16244 16243 16229 16003 15392 15185 15864 1999 14661 15162 16297 16794 17066 17169 16457 16153 16211 16305 15538 15405 16102 2000 15157 15974 16766 17658 17447 17100 16331 16497 16406 16215 15458 15212 16352 2001 14157 15697 16238 17046 17488 16798 16433 16763 16511 15502 14970 2002 14918 16010 16339 17410 17702 17414 16708 17209 16399 15995 2003 15927 17504 16939 17765 14887 15616 16197 16307 16443 16586 15421 15543 16261 2004 14103 15995 16824 17474 17346 17230 16801 16785 16770 16521 15603 15949 16450 2005 13967 16586 17095 17448 17661 16490 17258 17698 16796 16832 16533 16115 16707 2006 15882 16608 17677 18423 18960 19133 18068 18343 18211 17809 17287 16466 17739 2007 16239 17125 18133 18625 19324 18019 16852 17559 16804 17583 16125 15562 17329 2008 14453 16403 16716 17604 17457 16347 15596 15456 15834 16042 15796 15836 16128 2009 15662 17077 16864 17837 17042 16306 16054 16119 16160