Averaging out data from a DATEDIF Formula

Hi All,

Im going insane trying to figure out how to Average out the data i've accumulated with the DATEDIF Formula...Can anyone please clarify if this is even possible ??

Here's the situation...

I've got a range of data that has been calculated by using the DATEDIF Function (below):

=DATEDIF(H4,I4,"M")&" Months, " &DATEDIF(H4,I4,"md")&" Days"

This is working fine, im getting the desired results (eg: '3 Years, 5 Months')...however, i now need to calculate the average of my DATEDIF Results and none of the formula's i try seem to work ??

I've attached a small example of the Table that needs to be populated...Column E just needs to display the average of all the data in Column D...

Thanks in Advance for any help you can provide.

Cheers - Darren