1990 1991 1992 1993 ------------------------- Jan 12 10 13 8 Feb 10 8 13 11 Mar 6 9 9 8 Apr 4 7 9 10 May 16 11 9 17 Jun 9 13 12 16 Jul 11 13 12 21 Aug 23 17 18 26 Sep 25 19 22 33* Oct 18 12 17 24 Nov 11 8 9 14 Dec 6 6 7 10 ------------------------- 151 133 150 198 -------------------------*1993's "Summer of Lights" culminated in the highest recorded number of sightings--averaging more than one a day.