Based on the following sample data, I would like to calculate the average total time, as regards to single dates (not only time duration):
Date In Out Total Time
Wed 09/09/2015 09:00 17:00 08:00
Thu 10/09/2015 09:00 11:00 02:00
Thu 10/09/2015 11:00 14:00 03:00
Thu 10/09/2015 14:00 17:00 03:00
Fri 11/09/2015 09:00 17:00 08:00
Sat 12/09/2015 09:00 17:00 08:00
Average 05:20

The current formula that calculates the average in cell "D8", which needs to be modified, is
AVERAGE(D2:D9)
The result should be 08:00.
Is it possible to avoid using VBA or adding any columns to calculate totals per date prior calculating the average?
The MS Excel version is 2007.

The spreadsheet can be downloaded here:
example.xls

Any help???