it seems I have some problems reading your table. The last column is what you want to achieve?
In your sample data, I would expect to see the same value for any given combination of Period and Country, if you want to group by these 2 dimensions.
It looks to me that your last column is an average grouped by 3 dimensions (Period, Country and Type or Products).
What is the field / value you want to average? If you could post some lines of raw data, this might help in finding a solution for you.
If you just want to give it a try:
=avg(total<Period, Country> Value)
It looks more like a percentage share of products number than an average value to me?
If this is what you want, I think the last column is calculated like
= sum(Products) / sum(total Products) *100
and the second last column like
= sum(Products) / sum(total<Period, Country> Products) * 100
in a table chart with Period, Country and Type as dimensions - wait that won't explain your two feb-11 / Spain / D lines, how do you separate these two lines? There seems to be some dimension missing here.