Average time between events

[Fortescue]

Hi everyone,

so... I've got data in this format:

BLUMENAU |1 |3 |13/05/2008 10:20 |14/05/2008 11:02
BLUMENAU |2 |5 |14/05/2008 14:10 |14/05/2008 15:21
BLUMENAU |3 |1 |14/05/2008 15:43 |14/05/2008 17:51
BLUMENAU |4 |7 |14/05/2008 20:28 |14/05/2008 23:11
BLUMENAU |5 |4 |14/05/2008 23:26 |15/05/2008 0:25
BLUMENAU |6 |6 |15/05/2008 0:20 |15/05/2008 4:17
BLUMENAU |7 |2 |15/05/2008 5:40 |15/05/2008 6:49
BLUMENAU |8 |4 |15/05/2008 7:19 |15/05/2008 8:46
BLUMENAU |9 |3 |15/05/2008 17:34 |15/05/2008 18:57
BLUMENAU |10 |7 |15/05/2008 19:29 |16/05/2008 1:49
BLUMENAU |11 |1 |16/05/2008 2:38 |16/05/2008 6:20
BLUMENAU |12 |6 |16/05/2008 7:05 |16/05/2008 9:04

And I need a formula to determine the average time gap between the events...
ie:
14/05/2008 11:02 ---> 14/05/2008 14:10 is 3:08

I'm very new to this and have no idea where to start so any help would be appreciated.
Thanks

[daddylonglegs]

Lines 5 and 6 overlap so do you want to treat that as a negative gap or zero or something else? How you treat it can effect the average (and whether you count it as a gap at all even)?