YEAR Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual 24-hr Avg.
1998          17446 16114 15068
1999 15258 16355 16149 15107 13530 12756 12445 14032 14267 14827 12784 12321 14153
2000 12000 13373 13190 14946 13333 12519 12281 13477 12362 14053 12251 11827 12968
2001 11365 13161 12700 14416 13695 12465 12216 13946 14485 14621 12848 12364 13190
2002 12136 13623 13018 15430 14287 12995 12805 14247 14993 15231 14123 13143 13836
2003 12913 14370 13371 15678 14555 13504 13415 14795 15476 15880 13204 13231 14199
2004 12459 14204 14053 16091 13978 13512 13132 15105 15628 16210 13823 13120 14276
2005 13137 14572 14127 15728 14035 13379 12752 15123 14792 15133 13484 12287 14046
2006 13171 14138 13858 15180 13819 12977 12006 14194 14200 14513 12784 11851 13558
2007 12358 13307 13472 14586 12953 13304  16876 16721 17112 15930 14079
2008 14299 16254 15918 18429 16396 15112