Sum values in overlapping date ranges

[mattrogers]

We have a list of meetings including start and end times as well as the number of attendees that participated in the meeting. We would like to find which meetings have overlapping times then sum the number of attendees for each of the meetings that overlapped.

For example:

	Start	End	Attendees	Overlap Count
1	10/15/2012 06:29:51	10/15/2012 07:19:53	2	0
2	10/15/2012 06:59:56	10/15/2012 07:15:27	1	3
3	10/15/2012 07:21:31	10/15/2012 09:06:55	1	0
4	10/15/2012 07:31:40	10/15/2012 08:00:21	5	0
5	10/15/2012 10:00:52	10/15/2012 11:09:31	2	0
6	10/15/2012 11:00:26	10/15/2012 12:10:58	3	5
7	10/15/2012 11:51:00	10/15/2012 13:33:58	2	5
8	10/15/2012 13:33:03	10/15/2012 14:30:19	2	4
9	10/15/2012 14:01:21	10/15/2012 16:23:36	3	5
10	10/16/2012 06:59:33	10/16/2012 08:07:58	3	0
11	10/16/2012 07:29:40	10/16/2012 08:21:12	3	6
12	10/16/2012 08:04:36	10/16/2012 08:42:02	3	9
13	10/16/2012 11:31:25	10/16/2012 12:58:59	5	0
14	10/17/2012 08:02:31	10/17/2012 08:13:41	2	0
15	10/17/2012 09:01:01	10/17/2012 09:42:24	3	0
16	10/17/2012 09:56:36	10/17/2012 10:16:27	2	0
17	10/17/2012 11:06:40	10/17/2012 11:56:40	3	0

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As you can see there are several meetings that overlap with each other, but some of them overlap with more than just one other meeting. What we would like to be able to do is provide of number of attendees in the Overlap Count column of how many simultaneous attendees are in a meeting.

If you should have any questions I'll be more than happy to answer them.