YEAR Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual 24-hr Avg.
1990 14686 16758 17102 17620 17393 17572 16687 17061 18037 19218 18834 14850 17145
1991 15306 16962 17076 17993 17919 17585 17408 17655 17791 18242 16774 16595 17275
1992 16612 17791 18054 18673 17924 17968 17830 17840 19039 18886 17183 17512 17990
1993 16200 17197 18948 18767 18342 18997 18140 18262 18410 18364 17530 17162 18029
1994 16931 17585 19309 20327 18940 19272 18353 18366 18363 18364 17692 17091 18383
1995 17136 18324 18553 18954 18943 19774 18028
1996          18520 17134 16742
1997 16777 18097 18225 19204 19378 18972 18129 18423 18433 18500 17682 16787 18217
1998 16724 17821 18025 18659 18591 18775 17506 17588 18359 18618 17673 16966 17942
1999 16802 17735 18495 18623 18853 18819 18127 18197 18371 18765 17774 17388 18162
2000 17236 18087 18553 19041 18799 18917 17872 18378 18152 18383 17360
2001 16966 17827 18445 18649 18651 17993 17021 17188 18005 18015 17289 15869 17660
2002 16070        16603 15651 15828 16772 16289
2003 16662 16944 16484 17972 18037 17383 17171 17494 19950 18123 15898 16960 17423
2004 16035 15929 16170 16733 15974 16706 17552 18058 18815 18102 16935 16356 16947
2005 15495 16847 17593 18552 18272 18487 17092 18285 18711 17953 18161 18773 17852
2006 16606 16744  16306 16610 16808 15599 18979 19197 18163 17117 16036
2007 15441 16690 17500 18306 18809 17888 16554 18309 17664 17919 16474 15014 17214
2008 15097 16219  17361 17589 16838 16586  17347 17365 15622 17612
2009 15019 16065 16496 18124 18096 17915 17151 16856 17050 16982 15926 15641 16777
2010 15217 16402 16775 17609 16395 17074 16129 16657 16977 16831 17050
2011 15729 16055 15973 17006 16627 16729 16382 15662 16124 16150