YEAR Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual 24-hr Avg.
2004     27600 22279 23654 23061 21294 20037 18879 19037
2005 15783 18232 18936 19676 20824 22332 23689 24212 22198 19703 19046 17056 20141
2006 17344 18272 19152 19744 21299 22338 22956 22914 21047 19897 18398 17836 20100
2007 16007 17668 18966
2008  17785 17391 18091 19525 20388 21755